Heating while doing some tasks

My FP6 got a bit hot when lying in a bag while i was swimming two days ago, I then shut it off to prevent damage. Since then it works fine, no problems with charging etc. System check says everything is fine. The only thing that keeps bugging me is that when I use it to scroll on insta or play games it starts to get a bit warm (not incredibly hot but still noticeable) in the upper part (so can’t be the battery). Is that normal? I only remember noticing that one time in the past, maybe something to do with the warm weather? I don’t see any app running in the background.