Originally Posted by After Shock Media

Um dude this is common practice for not only gas stations but also often happens in restaurants. It has nothing to do with paypal either.

They do a quick charge to make sure the card has enough room as a buffer. Since they have no real idea on how much gas you will actually pump. Then they place the actual charge on your card when you finalize your pumping. This comes out of the hold amount and if there is any left over they quickly return it to your credit or debit card. Good news is that paypal adds it back fast unlike epassporte.

As for restaurants, they add a similar buffer for any tip you may wish to leave after you pay for your meal. Your buffer amount will not begin to be credited back until they run their credit card batch.

This also happens with all credit cards as well as debit cards.