"Yeah, he's just covering himself - no biggie. I mean, the MC called him on it and was like "Is it necessary" and his explaining it was clearly very fear-based and anxious, and she (I think) was trying to show him he is very fear-based with money but I just said it was fine."
Well, maybe.
It would strike me as very odd for a therapist to be critical of a client for handling financial matters between a couple no longer together in a businesslike way. He SHOULD be asking for receipts, and should have been all along. Indeed, the decent thing for you to do would be to provide him a receipt for prior payments.