Not really. In a 55 gallon long, I had a basking area that reached 90-92 and the snakes would sit there all day. That's fine if you can still manage to have the other end in the low 70's. It's when you heat the whole tank and have it too warm that you get problems. (keeping snakes too warm causes RI's) But really, magnarock you don't need a whole lot of heat for a garter and a wide gradient is important. You don't want to heat the whole tank. Air temp in the 70's and a surface which takes no more than 1/4 of the floor area, up to 90 degrees is fine. It just doesn't have to be that hot though. Even low 80's is adequate. As long as the snake can choose to cool down to low 70's, or warm up to around mid 80's or so, they'll do fine. Just don't force them to be warm. It's important for them to be able to cool down, or warm up as they see fit. Also, turn off the heat at night completely and let them cool down to between 60-70 degrees for about 9-10 hours. It should also be uninterrupted dark during this time.