I think 180 deg is max so it is a bit hot. I would lower the current setting a bit and see how it does. I have not heard of the coils going bad on a stepper yet so I would blame the driver for now.
If the stepper runs hot and drops more steps then I would think one of the driver transistors is smoked or leaking current.
You could flip the driver with the X and see if the heat follows the driver. If so it may have a problem or just the current setting is wrong. The switches don't always flip.