Yes, I check it. If it is more than a few beats above normal I'll tend to back off slightly that day if, as in your case, the higher HR is accompanied by my feeling a bit more tired or stressed than usual.
FWIW, I have recently started using
this. I didn't buy it, they're one of my team's sponsors. It purports to estimate stress (either from training, or illness or whatever) by measuring HR variability - the stressed heart shows less variability in rate between inhaling and exhaling, apparently. And despite my initial scepticism, it appears to work pretty well, giving high readings when I'm well rested and dropping the morning after a hard session. So it might be a useful addition if you're worried about overtraining.