Back when I still bought into the whole "women needta eat lotsa calcium" notion, and took supplements, I got palpitations all the time. I finally realized it was the supps. Like throwing a switch: take calcium supps for 2-3 days, I'd get palps. Stop them, w/in 72 hours palps went away.
But that's my body. There's no way for anyone else to figure out what's going on in your body. You have to be the detective.
Do you have health insurance? If so you might want to have your rhythm analyzed, if you haven't already, to at least rule out that it's anything potentially dangerous.