My ds was the same... sleeping through from just before 4mo, and only feeding 4hrly during the day (ie. 4 feeds per day). I too worried about it! But he was/is on the bigger side, so maybe that had something to do with it. Never fear though.. he doesn't sleep through at the moment (7mo)!! But I'm fairly certain it's not hunger related now. We only started solids at 6mo. He did have a week or two of not sleeping through at around 5m or so, but I just fed him, and then he went back to STTN. Maybe a growth spurt?? Or course I was advised to start solids, but I didn't want to/didn't see the need.
Enjoy it!!