I always check my motor temps by hand after flying as heat can be a good early indicator of problems. It is not unusual for one or two motors to be slightly warmer than the others and depends on how you fly. The drone maintains position in GPS, or turns, yaws, etc., by speeding up some motors and slowing others down. If you practice flying upwind for a while, maintaining the same orientation then bring the drone back to you, you'll see that the front two motors are warmer. Since I practice this way, doing the same maneuvers through a battery cycle, I often find one or more motors warmer.
Also, when you stop flying the motors will heat up temporarily since they've lost the cooling effect of the props and flight through the air. So, in my experience, it's not unusual to find a small temp difference but nothing to be alarmed about. If the same motor is considerably warmer every time after you fly, that may be an early indicator and since motors are cheap, I would swap it out and continue to monitor. Nothing sucks more than having a motor flame out during a flight....