I was just flossing the other day and looking at my teeth. I have to admit, I haven't done this often. But afterwards, I ran my tongue along the outside of my teeth and felt what appeared to be a divot of some sort. It was fairly large (larger than I would expect to be a cavity). To take a guess about 2.5-3 milimeters in diameter.
I took a closer look and it did appear dark. Of course it was in the back of my mouth, but the area was rather dark, but I feel no pain. If fact, I hardly even notice it unless I look or touch it with my tongue, which is surprising given its size. If it were to be a cavity, I would have expected to have felt it.
My last check-up was in May and there weren't any problems noticed by the dentist. I guess my only question is wether or not this it is possible, for it to be a cavity and to have gotten so large so quickly, especially undetected 5 months ago.