Hydronic baseboard heating

Just an update. We've been in the house for 3 nights and I'm fairly impressed with the system. Nice even heat and the boiler doesn't fire nearly as often as forced air systems and it's usually quiet.

I say that because the master bedroom is consistently 7* warmer than the rest of the house and I hear humming sound when the boiler is firing and I'm in bed. It can only be heard from the master bedroom and can only be described as sounding exactly like my wife running the vacuum cleaner several rooms away. No pops, gurgles, or clanks to be heard though, so I can deal with it.