Such instances are common anecdotes for many pets and others who have passed after at least several years of companionship. So, as a skeptic (or as close as I can currently achieve) I apprehended some things currently occurring to me. I have two cats that I have lived with for about 6 and a half years. I have found myself seeing one of them (or the other) out of the corner of my eye, only to look and discover not only that there was no cat, but that the cat was actually in another part of the room, or some other identified location. I have heard sounds that I thought were their cries, but further investigation proved that to also be incorrect. Usually, an alternate source was identified, occasionally not. Many times I have felt what I thought was the weight of their arrival upon my bed, or other furniture only to realize that was not the case.
So, what does this all mean? Is something weird going on? Something supernatural in some precognitive manner, for when they do pass?
Well, the first question will be answered beginning with the answers to the next two. Specifically, not all that weird, and definitely not supernatural. What I have come to realize is that since my pets have become engrained in my life, my experiences with them have imprinted themselves in my brain. I am constantly on the lookout for them, whether it be by sight, sound, or touch. My brain does its normal thing by associating even the slightest information into something it already understands (e.g., my cats). If more specific information avails itself that does not equal cat, then my brain obviously reanalyzes to interpret the correct reality. Normally, I wouldn't even give it another thought. However, after hearing the many stories about people having these same experiences with those that have died, I have realized that what is happening to me now is merely the mundane functions of my brain processing everyday information. I began to pay much more attention to these occurrences (which probably alters any "blinded" quality to my self-study), and though I can't say whether their frequency is the same, less, or greater, I have definitely become more aware of the circumstances that cause it. It was easy to conclude that because my body and mind had been "tuned" into making itself watchful to my cats' presence, it became sensitive to the slightest reminders/associations that might occur. IMHO, this is what has happened in wasapi's case, as well as the plethora of similar events others have experienced. While the subjects are still living, we tend to recognize these fleeting imaginations for what they are, and pay them no mind, as we quickly resolve the fact that our subject(s) Is (are) elsewhere in the material world. Once these familiar beings have passed, the associative events can be elevated to the realms of weirdness, because we are subconsciously unable to resolve them to an earthly existence.
As a final word, I have to add that prior to having my pets, I never had any of the false impressions that I related (at least none that I can recall). Anyway, that's me getting the most milage out of my 2 cents on the subject.