Oh goodness that makes total sense [except for the Comet explosions; I was born about 30 years later so any recollections I have of said explosions are literally supernatural!], because actually I put the cake in the fridge when it was a bit warm [uncovered] and not room-temp cool so maybe that caused the tension!
Also, before I put the cake in the fridge I poured the sour cream topping [according to the recipe it should be spread right before putting it in the fridge], and again, the cake wasn’t completely cool so maybe that had anything to do with it? Maybe because the structure wasn’t completely set yet, so when I poured the sour cream on top it weighed down and the part that wasn’t set “collapsed”? [I have no idea if that even makes sense, scientifically].
I guess I should have another slice before the linguistic police comes!
Edit: Oh, and Thanks!