This is an addendum to my original post:
In the end, I returned the iPad in question. Nothing to do with the iPad itself, simply a situation of not needing it anymore after solving an issue with the older model. Costco accepts electronic returns within 90 days with the receipt. At the Costco Returns desk, they clarified for me that the AppleCare was my responsibility to initiate, not Costco's. As I returned the product, it wasn't a problem for me, but if I'd kept the iPad, I was told I should go to an Apple Dealer/Apple Store and show them the receipt from Costco with the number on it and they would process the AppleCare for me. Seems the Costco employee I originally dealt with when I bought the iPad was not clear on the procedures for the AppleCare warranty. Hope this now helps future purchases if they too are told the incorrect information.