To ensure safe & secure online transactions & prevent fraud, Braintree (the company that handles our online payments) verifies credit cards by running a $1 authorisation and then automatically voiding it. While they do send a void request immediately following the card verification, some banks don't acknowledge those requests immediately, which could result in a temporary $1 charge on your statement. Unfortunately this is a mandatory requirement and it's not something we can turn off.
If you're confused about a lingering $1 verification charge on their statement, please call your bank and ask them to remove the charge; the bank can update your statement accordingly. Alternately, if you don't want to contact your bank, please simply wait for the verification to fall off of your statement. Either way, the $1 charge will never be completed.
Card verification is a strong first-line defence against potentially fraudulent cards, and ensures that the credit card number provided is associated with a valid, open account and charged successfully.