Possible respiratory problems?!

[Bettacreek]

I have four chicks that are about a week old. Three are cornish x and one is a barred rock. I was snuggling a chick a few days ago and heard a minute clicking when it inhaled. The rest had the same clicking. I know that clicking is supposed to be a sign of illness, but, they are growing so well and didn't show any other signs, so I figured I'd wait. They've been piling on the weight like nobody's business, but I noticed that one sneezed today. It wasn't a "wet" sneeze, just like it may have gotten dust in it's nostrils, not like it had mucous and such. Should I be worried, or am I totally overreacting? It's been awhile since I've raised chicken chicks.