I don't have a response like that to gluten, but I used to get a weird heart response to caffeine. Every so often, it felt like my heart would kind of pause and then it felt like it was flopping over in my chest (I know...weird description!). I'd have maybe 8 regular beats and then one weird one like that.
My doc told me that caffeine causes irregular heartbeats in some people. She suggested I get off it, and when I did, the problem went away.