@amerigirl86,
You know what, I have had three kids and the odd time I have had that problem, during sex, sitting down and getting up.. My last child is four and recently I have lost 16 pounds.. I notice when I suck my stomach in during sex it allows for more air to come in... Its a normal thing, that occurs and I have been with my husband for 10 years and still I get embarresed when it happens.. Kegel excercies are suposed to help with that.. I just recently started doing them to avoid the embarrasing romantic evening... Don't worry sweety, your not the only one, but sometimes it feels that way.. P.S. Try and make sure that he doesn't go in and come out all the way then go back in, more air will get pushed in everytime he re insertes he penis.. I hope it helps...