I don't think it's tastebuds because it is on the lingual frenulum, not the tongue.
Right now the white has subsided, I can scrape it off with my finger...so probably from salt water. But there is a small round bubble there at the very end of the frenulum near my gum under the bottom teeth. I was hoping Brian Hill might be able to help as posters have indicated he has a lot of dental knowledge. Thank you!