Lower Fat Percentage, Exact Same Weight

So, over the course of a year I have taken two quarters of a fitness class (in college!) and I have been eating somewhat better than I have in the past. I don't consume nearly as much chocolate as I used to, and I really don't eat processed foods or large portions. Anyway, my question is, if I have lost about 4.5% body fat over the year, shouldn't my weight at least be a little bit lower? I began at 28.9% or so, and today at the fitness center my body percentage was calculated to be 24.4%. My weight has been 150-160 lbs for the past several years, and my weight is the same as it was a year ago. I'm 5'6", also. Is it because I'm focusing on weight-lifting and only doing some cardio to warm up? Also, people ask if I've lost weight so I guess I LOOK lighter. Just wanted to check if this is normal, I'm sort of past looking at the scale only but it would be nice to see those numbers drop below 150. According to the BMI chart I'm borderline overweight, although I don't think that calculation takes muscle mass into consideration. I appreciate any responses!