Dang… Here ya go @BillC…
Lesson learned. Definitely add it to your contract. I think I’d be with @Steve on this one, but mostly to see if they’d accept partial responsibility. If they take the half and run it’s probably fair to suppose they knew it was some sort of a problem whether they get weather or whistling or bugs or whatever through that gap.
If they still raise a stink, I’d probably pay for the whole shazam if for no other reason than reputation management, but I’d add it to my list of questions to ask for the estimate and make sure it was in my contract.
Something like: Not held responsible water ingress for failed caulking, weatherproofing, gaps blah blah blah