KFCA said:
Yes. I guess you could say it was a "feeling" as I definitely wasn't also transported back to my old midwestern neighborhood. It was like being in a vacuum where I HAD to get back to school before the afternoon bell rang. Maybe like a "waking nightmare" if there is such a thing.
BTW, I'm perfectly willing to chalk it up to "mind tricks". I know that little apparatus can do some strange things.
I think this type of experience is more common than you might think. It was so vivid that it appears to you as a 'once in a lifetime experience'. As you said, you have run many times since and not experienced this trick of the mind. But you will never be able to create the
exact triggers that made your experience seem so real.
You were under stress not to be late for 'school' -- work. You had had a lunch -- heavy? Any alcohol? Caffeine? Any mushrooms?

))
Maybe you had a very important meeting. As Marian so rightly said, running can be 'mindless' and hypnotic. Adreneline is flowing, and regular sports people know of the 'high' they experience, especially after breaking through mental barriers. I know three people who are addicted to running. Two of them used it as a technique to give up mild smoking (like 5 cigs a day). Then they got hooked. Aren't we all 'hooked' on something?
Another clue might be your story about the perfume triggering a lesser experience. It may well have been a strong, long- unremembered smell plus the above that made this one so realistic. [like boiled fish, see below]
Smells that I seldom experience now, that bring back memories and a sense of place (albeit mild) include:
Primary school -- heavy smells of floor wax, wooden desks, plasticine, raffia (ubiquitous in classrooms at that time, it seems), chalk dust, crayons, pencil sharpenings, yucky paste glue (in buckets for papier-mache, smelled like marzipan), one male teacher who was a pipe smoker. Needless to say he didn't smoke in class, but always seemed to have a lot of 'meetings' where he left the class until the noise level built to a crescendo.
Wet coats hanging in cloakroom. Boys' toilet -- disgusting and disguised by industrial-strength disinfectant that smelled like -- disinfectant. Sanded puke. The slightly sickly smell of forty-two kids slurping warm milk all at the same time. (Oh, those class sizes!) I was a milk monitor.
Lunch time -- Friday -- milk-boiled fish in school canteen. I hated this then, but like it now. The canteen macaroni-cheese days. This smelled like a mixture of the warm milk and the sanded puke
If you ever go back to your primary school as an adult, it can be a genuinely moving experience with memories flooding back triggered by such smells.
Secondary school -- horrible, stinky, sweaty gym changing-rooms mixed with ozone/chlorine smell from pool. Stale smoke in boys' toilet. Woodwork class, mechanics class, and chemistry class smells. Disinfectant. Wet coats again.
The subtle fragrance of the most beautiful girl in English class when a teacher did the seating allocation and I got to sit beside Patricia. It was ecstacy, but for a shy lad, it was also mortifying. The experience must have been AWFUL for Pat since I literally doused myself with (dare I mention?) BRUT, as per 'Enry Cooper -- 'splash it all over'. We did Macbeth that term, and at 'Now, pat, now might I do it . . .' I was so besotted by this angel, that I had a 'blusher' of very crimson proportions as my secret teenage fantasies played tricks with the phrase. I was not thinking about murder.

Oh my, she was gorgeous!
Work -- office cleaning materials smells, a hot adding machine, an extremely hot co-worker, new bank notes. Later work -- the stale smell of beer in a bar, first thing in the morning, and smelly old bank notes. (Boy, that bank sure went downhill

) Oh -- other work -- boiler suits, hot machine oil, welding shop -- singed boiler suits, carpentry shop.
Anyway, I ramble on! I'd put your experience down to a stress and aroma-triggered, vivid flashback -- like deja vu on steroids.

Very interesting, though. If you were a JustGeoff-type, you might have believed the framework of time had warped and taken it as a life-changing mystical experience. But you've done the sensible thing and looked for mind tricks.