I have been using a straightrazor once or twice a week for a few months now.
Today I cut myself.
Occasionally I have barely nicked myself, but only once before--in my first week--have I cut myself.
It seemed like the razor caught on my skin in mid-stroke and, when caught, dug into my skin slightly--but enough to cut me.
I always stretch the skin, take short strokes, and keep the blade at around a 30 degree angle; so I was a bit nonplussed.

The first thing I did was curse.
The second thing I did was examine the edge on the razor.
I recently got this razor, and the edge looked OK.
So I did something that I typically do not do: the thumbnail test.
(I usually avoid it for the simple reason that I have been told it will dull the edge, even if seemingly imperceptibly.)
The edge ran smoothly on the nail until about midway, when there was a noticeable "bump."
After the "bump" the rest of the edge ran smoothly.
I did this three times, just to make sure, and it was the same result each time.
I believe this slight imperfection closely matches the point of the blade right smack in the middle of where I got cut.
I have not quite run into this before, so--

Questions:
Is it possible that a barely visible chip on the edge could cause the whole edge to catch in my skin, or am I mildly insane?
How do I correct this imperfection in the edge?
(If I can do this with a Norton 4k/8k, I would be happy to try; I just watched Lynn hone on his DVD, and this razor is not indespensable.)
How bad really is the thumbnail test for the razor's edge?
(If one or two strokes of the edge on the nail is useful and not detrimental, then I may do it before EVERY shave.)

Thanks, gents!