If he just got done doing the LIM gaskets, then yes, I would say he broke it. It is not necessary to take the sensor out to change the gaskets. But if you are not careful when you remove the LIM, you can easily break the sensor. So I would put my money on him breaking it.
But changing it is very easy. Buy the sensor. Put a little thread sealant on the new sensor. Remove the old one. Put in the new one quick. You shouldn't loose too much coolant, but check it and fill if necessary after a couple days.