steve you have nothing to worry about just belch or pass gas to get rid of the gas. bloat isnt reall that much of a problem because the GI tract of a human holds almost 35cf of air when total filled to capacity but not over pressuried (just enough to fill out the gut)
this information was given to me by my GI Doc
speaking of GI Docs, i have crohns disease whihc effects the GI tract. Diving for me and my doctor has been a learning experince for us because im his first patient,( i have been going to see him since i was 15 , im now 21) who scuba dives, ie effects of compressed gas on someone who tract is shortened, and the effects of the medications i take while on compressed gas( the drug companies are very intrested in these effects because of the implcations if something happens (its all good so far)).
Besides this i also have air go into my stomach with breathing normally so every so often my dive buddy hears a sound of like a tank creeking when i let it rip.
Also if you experince a sensation like your gonna puke, as unconvential as it sounds when in the water roll on you back and just relax because what this does is calm the stomach and release the pressure that is causing that sensation. If this doenst help after 5 mins, then your really gonna blow chunks unfortuanetly. if on the shore the same applies make sure your head is up so that you dont aspirate
FWIW