FB Wallet withdrawal

Not sure if this is the right place for this but here goes...

I had a wallet balance of $0.01 and purchased the €79.99 discount eGift card (great value by the way) but I noticed the wallet balance was withdrawn at the same time?

I'm not worried about it as it's just a cent but thought I'd flag it in case there is some other issue.

Screen shot attached for ref! :)