Is it normal for a natural to have some lower belly fat?

I am an all natural bodybuilder that has been training for 6 years. at age 18 I started at 125lbs and I now weigh 170lbs at a height of 5ft 9in. My physique looks great except for some stubborn lower belly fat. I realize this problem is due to some dirty bulking in the past to get my weight up but now when I cut my calories back it seems all of my gains disappear in front of my eyes. as a natural, is a little lower belly fat okay? or am I not doing something right