Report your card stolen. Again! Somebody else might try to steal a penny from you. 
Hey there. The same thing happened in my husband’s account. I guessed that this had something to do with the Gunbroker site.
The charge has also now disappeared but I’ll tell him to keep a close eye on his account.
I’d be pretty concerned about how they got my card number, too.
Since the pending charge has disappeared it was probably a means of verifying that the card is valid. When I buy gas at the local Shell station a charge of $1 (pending) appears on my online bank statement for about a day before the bill for the exact amount of the purchase goes through, and then disappears. Perhaps you’ve recently used the card someplace you’ve never used it before?
There a lot of good info in the thread so I won’t rehash. But this
sounds like bullshit to me. I used to manage the credit card systems for a large online merchant and when you put in an authorization, all the same information is sent as when you clear the transaction. There’s just a code that says it’s an auth instead of a purchase.
Did you actually call MasterCard, or the issuing bank? I’d talk to the bank.