Re: WTH!!!!!!! Silicone problem..
I have seen this happen with an industrial high quality Dow Corning silicone (forget the number). It clearly has a shelf life after which it changed consistency- didn't harden but was a little firmer than usual, and when I used it, it didn't cure as usual. Now that you've gone that far, I'd let it sit for several days and see what it does.
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio