If the disc temps are OK after pulling off the highway I do not think the overheating is related to highway driving.
DSC mostly involves the rear wheels and it's your front discs that are warping, so I also doubt this has anything to do with DSC, unless you have a wheel speed sensor issue that is causing the DSC to grab the front wheel but you would definitely feel that happen plus it would likely only happen on one side.
Note that braking too gently is a very common cause of warping rotors. Braking firmly for a short distance is much easier on the rotors compared to a long gentle braking period.
Straight lines are for fast cars...turns are for fast drivers
'04 M3 - track
'06 650i Cab - daily driver
'02 Highlander - kid hauler
'01 330Ci - winter beater