little flap on 3 month old gums?

On the bottom left side of my babys gums, like a little flap of his gum seems to me on it..hard to explain..and he always chews on his hand! like the flap comes out of the gum to where you can grab it...not that big just trying to figure out how to explain what I even mean....like you can pinch it if you had something real small to pinch it with. I have not pinched it lol like I said trying to figure out a way to explain.

Hi, I think my baby girl has the same thing and I don't know if it is normal? Did you every figure out what the gum flap might be? Thanks!