My youngest does it too, exactly as you described it, mommyoftwo0609.
I'm not sure when it started, but she was very little.... maybe from birth, but I can't remember. And it wasn't very often back then. I just remember that she was tiny and making weird sleeping noises. I didn't think much of it at the time, because they always make weird noises when they sleep! Then she did it more often starting around 3-4 months, but still not very frequently. It was one of those things I thought maybe I should pay closer attention to, but with 2 other kids, and the fact that it wasn't a regular thing, I kind of forgot.
Then it got more frequent around 5 months and became a fairly regular thing between 5-7 months. I video taped her one night and showed it to my doctor and he said it was weird, he had no idea what it could be, didn't seem like apnea or reflux, but it actually looked more like night terrors, but he'd never really heard of babies that age getting night terrors! He offered to refer her to a specialist, but I declined and decided to keep watching her. He did listen to her heart and her breathing and said she seemed normal.
So, "night terrors" can be set off from a child being overtired or over stimulated throughout the day, and as I thought it through, each gasping incident usually followed a rough day where she didn't nap as well, or was just really over stimulated that day, or if she'd had a rough night the night before..... so where I don't think she's actually having full blown night terrors, I have been able to put it together that the gasping incidents are caused from her being overtired, where she just can't settle down into a good deep sleep.
SOOOO, to summarize the rambling.... pay attention to your baby's sleep schedule and her daily activities and see if that doesn't have something to do with it.
Oh, and my baby is 17 months now and she still does the gasping thing on very rare occasions, but she's mostly over it (maybe because I make sure now that she gets good sleep and good naps?).