I don't have an answer for you, but I'm wondering the same thing about my 4 year old. It never happened to him until this past Christmas while we were in the Bahamas and then it happened again over the weekend when he was staying with Nana and PapPap in the D.C. area. Mil (Nana) says that my dh had asthma when he had colds? Not sure if that makes sense or maybe he just tended to wheeze when he had a cold. I'm interested to hear what others have to say.