Mimi and Nick hit Nobu Sunday night for dinner with their twins, Moroccan and Monroe. Makes sense the kids would be with Mariah on Sunday ... the fact Nick joined them just adds to the buzz they're getting back together.

Nick's told us it's just a family thing, but after the trip to Disneyland a few weeks ago, and a string of dinners together -- and not always with the kiddos -- it makes you wonder.