
Please keep an eye on it and check the rest of the mouth and throat to make sure none appear in there. I am not trying to scare or worry you as the chances are very slim indeed but I had two little CKCS who had Auto Immune disease which caused ulceration in the mouth or throat.
It is more likely that your dog has bitten his tongue and because it was sore keeps playing with delaying healing time.
If it gets any bigger or anymore appear then I would get them checked out.