I Have A Loose Flap Of Gum Behind My Front

I have a loose flap of gum behind my front two teeth (almost near the roof of my mouth). I have had it for several years now, and it has never caused me any pain. However, as of recent, it has hurt when my tongue or retainer touches it. I have several questions regarding this:
1. Is it normal? (If not, then I'd like to know who to see about it)
2. How can I get rid of the pain that it causes?