It would have to get ungodly hot for that to happen and you'd most likely have warped heads by then (if not a cracked block) but I suppose it IS possible, and if you're located in Santa Monica I guess the chances of you seeing freezing weather is all but zero. And then again, the car would've had to been parked in the cold without moving/starting for quite some time for them to pop - unless it was somewhere horrifically cold it wouldn't happen overnight. Engine's aren't THAT fragile, not by a long shot
Just out of curiosity, did you know the PO or how the vehicle was cared for previously, as in here they might have taken it or why they listed it for sale?