I was so pissed about the Premium thing I went back and checked. The credit card for auto-renew was saved as "NULL" for some reason. Sorry for everyone else running into this issue - I feel stupid lucky I just happened to try to preorder the two-pack the hour before and got cockblocked by not being a Premium member anymore so I had time to renew before noon. What a mess.
EDIT: I got SHIPPING NOTIFICATION for my Premium Membership at 12:41 p.m. today. After I'd used it to buy stuff. They better be sending me a goddamned fancy pants membership card with Snake Eyes fist-bumping Wolverine or I riot.