I had dissolving stitches on my tongue when I was like 6 or 7. I don't remember how long it took for them to dissolve. But i'd figure that if it were the same kind, then your shower didn't do anything (because mouths tend to be moist). If it's not splitting open at all, then I wouldn't worry about it. I mean like if it's holding together ok. Maybe a "band-aid" (gauze and tape, whatever works) would do. If you are really worried about it, call your doctor's office or a hospital hotline and ask.