I got charged $2.00 from Google, I don't remember authorizing this charge.

When you add your STACK card as a payment method in digital services such as Google Play Store, Netflix, Staples, etc., it's common for them to request a small amount $1.00 or $2.00 to ensure the card is valid card number.
You will see the amount deducted to from your balance immediately, however the small amounts are generally released back into your available balance within a week (they're on hold). If the amount is not released back into your available balance after a week, please contact the store to have them issue you a refund.