Kara - I have noticed the same thing in the last few months, but mine is more of a ridge that lines up with my bite along the left side. I have just assumed it was from biting my cheek (although I don't remember doing that particularly often). Recently, however, certain foods have been causing it to swell, and it is getting bigger. I have just recently started getting concerned, which is what led me to this site.
I now feel a thickening near the corner of my mouth on that side so am planning on seeing an oncologist -soon-.
I hope you do the same, just in case. I'm praying that, for both of us, it will turn out to be nothing.
- Ed
www.Godhastheanswer.com
Is it back toward your molars? If so, it might just be from biting your cheeks. I have TMJ and my mouth doesn't line up right so I'm always chomping on the right side of my cheek...the left sometimes too but not nearly as bad, so the injuries on the right side are much more prominent. Just an idea, if you're a cheek biter :)