Bump on my dog's gums.

When brushing my dog's teeth (which I know I don't do often enough) I found a bump on his gums. It's pretty big and hard. He's 6 years old, so I'm pretty sure he's not teething. When I put pressure on it, he doesn't react, so I think it's probably not painful.
Has anyone experience this? Does anyone have ideas of what it could be?

Welcome to the board, Buisty!

Probably the only way to find out for sure what the lump is would be to have a vet look at it. It might be an abcess or a skeletal issue. Or it might be something as benign as an epulis. A vet will be able to tell you for sure.