Agree with those that say that you are probably over-layered of you are toasty leaving the house.

I usually spend the first mile telling myself that I will put another layer on when I get to the two mile mark, the second wondering if I need to, and the remaining 8 miles (up & down) increasingly glad that I didn't. I have an outer jacket that vents well, very good for the last bits, even when it is very cold. I think the key is to regulating how much you sweat in the first place, i.e., don't let yourself get overly warm at the start.

Anne