It definatly sounds like he's hiding something. Maybe he has more assets than you think or maybe he's broke and embarrassed.

Is the current settlement close to acceptable to you? Do you have what you need to move on? Custody, child support, alimony, assets split ok? Only you can decide this. If its close might be worth it just so $$ isn't sent to attorney fees. Not trying to give legal advise just offering questions to think about. Besides if its close whos to say you cant change your mind at mediation? Again I don't know your financials so only you can figure out what to do. Good luck!