Thanks for replies. Fortunately it looks like I was getting way too jumpy about just one failed frame.
I have taken two more shots since, they developed fine. One room temp and one at around 1 C, this time not under my coat but in my bag. I wanted to experiment.
The room temp ones have very deep contrast and the ones around freeze point have a faded look. This is to be expected. Polaroid gives no promises below 13C. I only was bummed about the third shot where it obviously didn't start to develop right at all. It might have been a user error, maybe. Perhaps we'll never know.
I'm too cheap for Polaroids for my own pleasure. Taking just three shots is costing me more than an (employer-subsidized) lunch. Not my game, Polaroids. I'm glad the camera works fine (within 5 frames managed to test all the features: autofocus close and far, self-timer) but I'm urging the recipient to be careful while the camera is ejecting the frame out: if it was a user-error it must have been something during that one second in time. Or maybe the individual frame was just faulty from the get-go. I understand this has always been a part of the Polaroid experience.
Just for funsies, I'll post the frames tomorrow.
Perhaps I'll even ask the larger Polaroid community about educated guesses/opinions about what sort of malfunction might have caused the failed shot: developer chemicals not activating, or something about the chemical layers, something else.