Your tank will get warm with prolonged use for sure. So long as it's not your battery / device getting hot, it is probably normal and you needn't worry about it.
Now that said, if you are getting burnt or dry hits, notice your battery or mod getting hot, see smoke (not vapor), smell burning plastic,
experiencing weird flavors or discomfort, then something may well be wrong. You did say 'rly hot' - that is not normal, but it depends on your definition of hot.
What battery / device are you using and what settings do you have it on?