Kitty with runny nose

Ok- so my kitty has an occasionally runny nose. I might notice a little wetness once or twice a week. Its usually just a little bit of clear fluid coming down one nostril usually (one at a time, but comes from both), but not usually enough to even some out of the nostril. This morning as he nosed me awake he actually dripped on me (ewww) but its generally never that much. He has no other symptoms- eats fine, no sneezing or snuffling, no runny eyes, no face rubbing, no facial swelling, etc. Can cats just have a touch of allergies? I mean, I wake up with a stuffed nose and puffy eyes every morning thanks to my allergies, could he just be experiencing something similar? I told his vet about this the last time he was in (about 3 months ago I think when he turned six months old) and she looked in his nasal passages and said they looked clear.

Could he just be allergic to dust or somewhat? Maybe he needs some Kitty-Claritin, haha?

We had a cat one time that dripped when she was happy. She loved to 'hug' you, sit on your chest w/one paw on each side of your neck, and purr away. Every now and then, though, you'd feel a cold trickle down your neck - her nose had dripped on you!!!!! She wasn't unhealthy, just very content.