heated grips

Hi, I've had honda heated grips fitted to my fireblade and they keep switching themselves off. The dealer seems a bit reluctant to accept this as a fault saying that "honda grips do sometimes switch themselves off". This doesn't seem right to me and when I first got them, about three months ago, it didn't happen then.

Anyone experienced this sort of problem, with the grips or dealer?

Thanks, Stegzzz