M_Boats: m-15 reefing question

This past weekend winds were well over 15mph, with higher gusts and changeable from south to west, so I tied in a first reef on the main and used my smaller jib (78%). The sailing was great with two additional passengers, but I seemed to find myself with a lee helm when not hard on the wind. Is this usual in this setup, or did I do something wrong? On another note I recently sailed with a Core Sound 17. He finally left me behind, but it took a long time, which I was pretty happy with since he had 2 feet more waterline.