Hey cool, I was wondering if that was only me, and if it had a name.

I think it happens to everyone in small amounts. Low blood pressure seems to be a common culprit for me. If I get super-relaxed, like after a yoga class or a good workout, I can actually see my heartbeat. It's weird, and it was unsettling until I figured out what it was.

A close friend of mine has HPPD, and although I can't speak directly from experience on that, it seems to me that much of HPPD is an anxiety reaction to normal visual phenomena that most people grow used to and filter, but for which people can develop hypersensitivity and then become convinced that something is wrong. (This would be much like how, during the onset of a severe panic attack, especially in a person who has never had one before, normal semi-liminal physical sensations morph into "evidence" of impending doom/insanity.)