I used packing tape to get the little shards of glass off the bed & pillows last night, then vacuumed everything today.
The whole window moves just fine still, so it's not like the house settled & squished it.
I guess it was just pressure from the air in the window? It was pretty cold outside last night, and around 60 in the room.
Lee said he thinks these windows have a lifetime warranty, and I'll find the receipt.
Still - what a weird thing!