Well, if the other snakes were being housed with this one at one point, they were most likely sharing water bowls which means they all could very well have it.
I personally would wait until the snake finished the shed cycle. If you still hear the noise, still observe face rubbing, or if you see mucous or hear popping and clicking, take the snake to the vet.
If treated early on, a respiratory infection is nothing to worry about. It is when you let it go that it becomes a problem. Be aware that there is no home cure for a RI. You need antibiotics. You will be more successful if your vet does a culture on it so you can treat the snake for the right thing. Some RIs are not affected by baytril injections.