Once in a while, my 735XT's HR monitor would act crazy and show ridiculous HR numbers. It usually happens during a run. When it does, it wouldn't go back to normal till the end of the run. That'd completely mess up with the stats of the run. I can't seem to find a pattern but it's been happening quite frequently lately, like, once or twice a week. I suspect it has something to do with the humidity.
Has it happened to anyone else?