This is tough to describe, but here's how it is:
This seems to only happen when I'm looking at my computer monitor or the TV. Sometimes I'll notice a tiny black dot on a wall to the right in my peripheral vision. When I go to look at it, it's gone, and I cannot reproduce the issue. This may happen a few times each month, each time unexpedidly. For all I know, it may be my paranoia that's causing it, but I don't know. I spend a lot of time in front of my computer monitor too. I know I have a few floaters, but I don't think this is it because the "black dot" is not moving, and it always seems to be on the right side of my vision. and again, the dot is never actually there to begin with.
Could it be persistence of vision? I had a full eye exam two years ago and everything was perfect. I'm 35 years old, in perfect health, not taking any medications.