Glad you found the broken rivet ... well, no, not glad ... but hope you found your problem! (Although a broken rivet to a true fiberglasser, is a badge of honor ... besides, it's fun and easy to fix!)
As you said, remember to caulk the hole first, before inserting the new rivet. Remember to put on the snap cap base first!
Your wife sounds as busy as mine! I occasionally will draft a friend or stranger to help put in an acorned rivet!
Check the rest of your rivets, ok?
And like Pete (and others say), remember to vent your rig as much as comfortably possible during cold weather camping!
Keep us posted Roy!