darmae, think ur bb is just tired lah, therefore sleeps longer, my baby sometimes also will sleep longer while other times will be restless. Actually daytime shld wake bb up for feed, night time is ok if bb don't wake up for usual night feed cos' ultimately we want bb to drop night feed.
If bb don't feel full during daytime feeds, they will tend to wake up at night for feed, that's what my auntie told me.