There probably is something the captain needs to get off his chest, any number of somethings, but he can't quite put words to any of it. It's unsettling, all the things he's feeling.

All because of a tiny girl who now lies sleeping just across his quarters.

So because he doesn't know what else to say, he just says, "...Yeah. Hell of a day." He smiles faintly, adding, "Maybe I should've had a nap when she did."