Yep, when they are quiet and even going out on the limb to say communicating and being nice, you have to keep on your toes. They always have an ulterior motive and he knew you would find out about the account when you tried to get money. My xh did something very similar w/his direct deposit salary check long ago. They don't have the guts to tell you what they've done, so they do it this way, thinking it's sweet revenge for you to find out. It's a passive way of doing things. I wouldn't say a word to him, but I would let my lawyer know about it very quickly. Don't let this slide because you need to have this documented w/the lawyer.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.