04Subie

I just got my first Subie, an 04 OutBack. So far the car is fine. I am wondering about the cruise control. I set the cruise on 70. It stays solid on 70. If I accelerate to 75 and ease off the gas, speed drops to 66-67 and then eases back up to 70, where it holds 70 solid again. I haven't experienced this in other cars I've owned and wonder if this is normal in the OutBAck?