Same reason your BBQ tank "sweats" when your BBq'in , Common on Trams and blowers etc Tom
ps .. Cool fuel antomizes better like Terry said its a "good thing"
Actually its "warm fuel and cold air", just really hard to achieve...

Our race boat had a fuel cooler that was actually running hot water, right before the carb, warmed the fuel just before it hit the motor, then we had a 2" open spacer under the carb.
It ran very hard and the tuneability was incredible (ran richer when cold because of the puddling fuel).

Old Sprint car trick (mechanically fuel injected)

GT