URI/Upper Respiratory Infection Could it be another one?

This morning, I went to go give the boys their breakfast and I heard Louie sneeze two times. Both boys occasionally sneeze, but being the over protective mom that I am, I freaked out. I picked Louie up, looked at him all over and checked his eyes and nose. His eyes are clear and look good but he had some clear discharge out of his nose. I haven't heard him sneeze again and I'm wondering if this is an early URI. He has had two in the last year that I have owned him, and I caught both of them pretty quickly.
Luckily, I work for a cavy-savvy vet and she told me to bring him in to just be checked out. I just wanted to get other people's opinions if I should bring him in or not. I know I shouldn't wait if it is a URI because he can go down hill fast but if it isn't a URI, then the whole trip and car ride will stress him out! But he is 4 and I worry about this being another URI if there is something more wrong with him!
Any advice would help!