How come a wheeze when I inhale?

I had smoked regularly for about 8 years, but have since slowed down to practically nothing. I work out regurlary and run 3 miles a day without any real problem. But sometimes when I take real deep inhales I get a wheezing sounds that is usually cleared up with a cough. What could this be and is it something I should be really concerned about. Like I said its only when I inhale, not exhale. 28 yr old male