Yeah I'm feeling a little unsure myself after reading these replies... I had a checkup very recently and got the all clear... The most recent incident I was referring to (I hiked up 5000 feet in a couple hours and ran the descent) caused severe DOMS, and I think the elevated RHR may have been due to muscle damage in my legs. I was probably not physically prepared for that large of a running descent. But I'll keep an eye on it.