Are you guys sure you're not dating the same girl??
Ha ha, just kidding.
Everyone grieves a little differently. She may just view you as a knight in shining armour who helped her through her most difficult time. Or she may want to curl up like an armadillo and keep everyone out. I don't see anything wrong with being a shoulder to cry on, if she WANTS that. Let her set the pace though, so you don't become the creep that took advantage of her vulnerable state.
Keep us posted!