Seems no topic on here gets out of control. OP, you will be fine at those temps especially if you drained the lines and leave the faucets open. It would take a lot more than the temps and times you'll see to freeze pex and fittings, especially if they are not under pressure. Since we moved to NC, we've seen very few days that get below freezing but it happens. Once at 27. Never winterized and never had an issue.
I guess technically speaking delamination could happen if the right conditions were present and freezing and water under pressure were at the root. Pipes would have to freeze, water pressure (not present in this case) would shoot water everywhere, that water would somehow have to find it's way into the wall and between the fiberglass and backing and freeze again to lift it away from the adhesive. Pretty unlikely but I guess possible. Might win the lottery too. Delam happens when the glue comes away from the glass. It used to be more common until they changed glues in more recent years. It was also more of a result of roof and window leaks than broken plumbing, but it could happen. If you had water intrusion bad enough to cause delam I would be more concerned about all the other stuff that was ruined too.