you would be surprised how many times clothing is marked to wash in cold or cooler temps, can really withstand hotter temps....
if my sheets were labeled COLD WASH ONLY, I wouldn't buy them....then again, I would wash them in HOT no matter what....
and, if your using a dryer, your dryers temp is hotter than what most water heaters can reach!...
unless your dryer has a modulating heat source, the LOW setting still climbs upwards of 160+....then cools down until it reaches a temp of 110/120 before firing up again...
I have backup sets for the beds if needed, but always liked taking them fresh out of the dryer and back onto the bed...I keep spare sets in the closet, top and bottom sheet stuffed into the pillow case, folded over and placed on the shelf, saves times from searching for all the pieces when needed...