What is my ex thinking?

After 6 years of marriage, my ex announced he wanted a divorce. BOOM. It was over in 90 days & I was devastated. I never wanted the divorce. Our problems were very workable...no abuse, no infedility, no financial problems. It has been 9 months & my feelings are the same. I love him & never wanted the divorce, but I've forced myself to move on with my life. I have a new job, am doing well as a single mom, go on dates & spend time w/my baby, friends & family. Last week my ex called to tell me his cousin is divorcing & he advised him not to rush into it because there are days he feels he made a mistake. I was stunned when he relayed this conversation to me. Now, tomorrow is his nite w/our daughter but he's invited me over for dinner & he wants to grill out. We never spend time together & this is very odd behavior. Our lives have been TOTALLY separate since he dumped me. Between his advice to his cousin & this unusual dinner invitation I'm wondering if he's changing his mind. Or, am I being foolish thinking that. He says it's good for our daughter to see us get along whereas I think she's going to be confused. Does he want me back or just (for some reason) wants to have dinner together? And, do I go?