Weird 'whickering'?

I have a cat, about eight years old, who has just recently started making a weird whickering or fluttering noise - it's not a cough, and it's not really a sneeze. It's like... a shuddering outbreath. Her nose is runny, but she has no fever and still is fairly active with our other cats. It isn't the same as Copper's (another kitty) asthma symptoms, so I was thinking maybe it's a URI? It's hard to explain, and when I tried to video tape her, of course she didn't do it. Any ideas?

It's possible it's allergies or upper respiratory infection. I'd get him to the vet.