You made no mention of cancelling your old card. Therefore, it would have automatically transferred to FNBO. This is unlike past transitions, where your old AGR card became some generic card by that bank and you had to apply for a new one. In this case, B of A sold the account portfolio to a new bank, and unless someone specifically cancelled their account more than a month (?) or so before the cutover date, they would have automatically have been given the FNBO card, and all account records and history effectively transferred over.
If you had cancelled the old card, the charge would have been declined. If you just left it in a drawer and forgot about it, never expecting to use it again, then you’d have a new FNBO account.