Sounds like it was running rich when you took it in, and now it's running right. They're not supposed to be good when cold, most british engines with carburettors require about 1/3 - 1/2 choke for about 2-5 (depending on weather) when they're cold.
That's not a bad thing - it reminds you not to hammer the engine till it warms up. That's the fastest way to kill them as the oil's still thick and the bearings still tight.
