losing inches on waist, but not hips.

Ok, so I took my measurements today and noticed I'm losing inches in my waist, but I gained in my hips...I lost and inch and a half in my hips, then gained an inch back, butnin my waist I lost 3 inches...no gain back. I've dropped 21lbs so far. I guess I'm just confused on the random inch gain. Any ideas?