Sounds like a sticky pawl: flush with wd40 (to break up the factory grease) then lightly lube with whatever your heart desires.

As an [somewhat] aside, how do you store the bike? I'm noticing that the brifter bikes of mine I hang from a rear wheel seem to have semi gummed up shifters when I take them down to ride. Also, the factory grease doesn't take all that kindly to the cold.