Update:
I just picked up my car. All is good.
As others here suspected and myself (I mean, according to physics is it even possible for the car to overheat within a few seconds?) the car was not, in fact, overheating.
At the dealer it was interesting, because I couldn't really get a straight answer or real details from anyone except for this: They reprogrammed a "module". They were hilariously non-specific about it. After re-programming the module, they monitored IR temperature, pressure tested and did the usual search for coolant leaks, etc. and everything was checking out completely normal, on both a road test drive yesterday and again this morning.
It sounds like this was a situation they are familiar with, but they are not admitting to it in any formal sense. Basically, if you bring in your car with these symptoms there is a procedure to deal with it, but they aren't going to put that in writing.
So if your ST does a similar thing, you may be lucky enough that it is simply a problem with the programming for an engine management "module".