They made me do that when I made an offer. Initially I thought it was just for offers...now I've read it more carefully, and it says auctions, too.

However, today I bought some matchbook covers. The seller offers discounts, and combined shipping, and I did receive an invoice that I paid. They didn't do anything automatically (at least not this time!)

You’ve selected PayPal account ****** as your payment method for the offers and bids you make on eBay.

For your records, we’ve included a copy of the payment authorization:

“You authorize eBay to link your PayPal account to your eBay account and use it to collect payment from you for items you offer to buy or win at auction on eBay.”