Never had it happen to me but then again the only time I reliably squirt is when I'm pregnant so I might have attributed the pain or any discomfort to being pregnant. I wonder if there is any strain to the kidneys during this process, or if it's muscle pain near the kidneys causing the discomfort. Might be something worth talking to a Dr. about, but then again my Dr. is used to my odd curiosity and indulges me. He'll look it up if he finds it odd as well.
I know we have some health workers in our community maybe they can weigh in on the topic?
If the pain is severe I would say talk to your personal Dr. it's never good to dismiss discomfort.