In all seriousness, I have had one vendor (not to be named here) that had juice that, for whatever reason, had this effect on me. This only happened with this one vendor, and it happened with all of her juices. I tried each one on different days, but no matter what, those juices got my stomach rumbling.
We're all adults here and I think this is a valid concern/question. My guess is that it was her nicotine. No other vendor or juice has had this effect on my system (thak GAWD!)
Now, if you're saying that you were a non-smoker, that may have something to do with it, but it may not. Is this with any and all juices (different vendors), or a particular one?