Sorry about your kitty, and sometimes they do make the decision like that.
Over the years I've discovered several of our outdoor cats curled up in a hiding hole where they chose to go to pass. If we know they are having issues, we deal with that but sometimes they just go off by themselves and you always wonder.
I'm OK with shipping early - I'll be heading for vacation on around the 16th so if it gets shipped early enough I'll have it before we go. We have our mail held so even if it does not, that won't be a problem.