I assume you have what Avid calls 'Ball Bearing' brakes. If so, then it appears that there is a tension adjustment on the caliper for the brake return spring. Is your caliper adjusted the same as your friends? It sounds like your brakes are set up with a higher tension than his.

Failing that, check your cables and housings. Perhaps you need to pull the cables and clean/grease them or replace the cables and housings depending on how long and where you've been riding.