Definitely a thought I also had. And yes, I go to all my six-month checkups. Better a cavity than cancer! Since I've pinpointed the area, that's where it bleeds. I dunno. One conforting thing I read is that oral cancer isn't the most common on your gums near your teeth.
The thing is, I have discoloration on my teeth, so I've dark spots before that weren't decay. But like I said, it's difficult for me to see back there.