Earlier, I was complaining about Chase Visa's customer service. Now I realize what went wrong, and I feel chagrined.
After my initial PayPal charge failed, I changed my PayPal account's primary credit card to my Costco AmEx card instead. That explains why my charge went through the second time around. I'm willing to admit when I made an error.
Still, I'm annoyed. My Visa card had not yet expired, yet they already chose to decline its use. That's annoying and just plain wrong.