I'm not exactly sure of how this goes, but we have the weepy eye thing here too. It has to do with the herpes virus and/or calici virus.
I don't think it passes from cat to cat in the form of the URI, but once a cat has had a URI they can carry the weepy eye (similar to humans carrying the cold sore [herpes] virus)
Some cats have a resistance to it, and never get the weepy eye, and some get it routinely.
I can pinpoint which foster cat brought the weepy eye thing here, altough she wasn't sick with URI. Now, Snowy and Mr. Jones get it and Bella never does. Malfi gets it once in a while.

In a nutshell, it doesn't mean yours will get it, they may or they may just carry the virus.

maybe someone can post some medical facts on URI, herpes and calici.