Oh good, it's not just me!! I have been feeling the same thing for a couple weeks. Wierd huh? To be honest I know it's not, but I like to imagine it's a preview to actually feeling the baby move in a couple months.
To me, the early movement felt exactly like the fluttering/twitches or like little bubbles. I felt my 1st at 17 weeks and my 2nd at 15 weeks. It may take a week or so to recognize it as the baby and not just gas at that point.