Usually not a problem unless your airlock is overfilled. I would go with plastic wrap myself but mostly because there's not enough headspace for the airlock in my fridge and I don't have caps for most of my carboys.
Originally Posted by Robusto
"The main ingredient needed is 'time' followed closely by 'patience'." - The Bishop 2013
"Good grief! If someone wanted to murder you, all they would have to do is ship you a 55 gallon barrel of honey and watch you document working yourself to death!" - Vance G