Hi mrdsbaker,

It's nothing to worry about, I had the same question when I registered.  (I think there should be a notice about it to save unnecessary questions).  This is the response I got:

The $2 is an authorization (which is a temporary hold, not a charge). We do this check to verify that the information that you entered is the same as what is on the card (fraud check). This amount is dropped and not charged. The time it takes for it to drop off your card depends on your bank's policies.

Please let me know if you have any further questions/concerns.