When most manufactures give a temp rating, they are expecting you to measure the hottest part of the can.
Remember that if the motor can is very reflective you are aren't going to get a true reading from an infrared temp gun.
I try to get the measured temp on the inside, measured through the vent holes, then try to get the temp on the outside as similar as possible.
This means the can is conducting the heat away well.
If there is a big temp difference then you are effectively cooking the stator on the inside.
Remember, the can just holds it all together, it's the stator that gets hot.