Paypal offers several different ways of submitting payments to vendors.

1. ACH from your checking account. This is when they debt your checking account. This has caused delays for me in the past because they will not guarantee payment until they actually receive the funds from your bank,
2. They can also use a credit card to fund the transaction, and
3. Pull it out of your paypal money market account if you have one.

If I don’t want to wait, I’ll use option 2 unless I have some money sitting in the money market account, which does not happen very often.