If you mean the strip type of thermometer they are not very good to use as a main gauge. I would suggest buying a IR temp gun(Amazon $20). That way you can see what your surface temps are. Just because the air temp is good that does not mean your surface temps are correct.

Also after feeding most snakes do not move for 3-4 days. During this time do not handle it. Handling could cause it to regurgitate it's meal which is very taxing on your snake.