Hi,
The skin flaps you are talking about are may be a little soft tissue overgrowth in mouth.
Next Steps
Mostly they don't cause much problems so can be kept as it is. In case when you bite on them, you may get ulcer there, at that time you can apply REXIDINE GEL on that,keep it there for 2 minutes and wash off then.
Other option is to get those flap cut and removed through LASER, but chances are there that it may regrow.