Nub on gum

Today when Smokey yawned I noticed a little nub on his gum. I felt it and it feels hard. It doesn't look inflamed or infected and it doesn't seem to be bothering him (he's eating okay). I couldn't tell if it hurt him when I touched it cuz he was moving around anyway since I had my fingers all up in his mouth . I'm going to keep an eye on it but has anyone seen this before? I wish I could show pictures but I have no camera.
The nub is on the bottom gum right below one of his back teeth and feels hard, like I can't wiggle it around.

I should note that in Oct 2002 he had his gums stitched up after he was in a fight. But I don't recall if it was in this particular spot.

Thanks in advance.

It could be the equivalent of a cold sore, or a localized infection, or an outgrowth of bone, or... melanoma. Have the Vet examine it.

Well Smokey had this little nub on his gum removed today. All went well, no excess bleeding which I was worried about from last time he had surgery.
I'll get the results of the biopsy in a week , the doctor is pretty sure it was a benign tumor - an epulis .
I guess we'll just have to wait and see though.