my ferrets eye is watery when they first wakes up

[Deleted]

Hi my name is Brandon I own 4 ferrets and care very much about them .recently I noticed 2 of my boys have a watery eye when they fist get up I'm wondering if it could be from my corn cob litter , I normally use carefresh  litter ... Is there any way to know if it's just allergies or dust without taken them to the vet ?... Don't get me wrong I'll do whatever I gotta do to make sure they are ok!!any help is very much appreciated thanks. 

[Sherry]

Are they being affected in any other way? Appetite, activity level, sneezing, sounding congested? Have you changed anything else(laundry detergent, using air freshener, YOUR cologne/perfume)
It is possible they are allergic if this is the only change.