Yes, always quarantine at the first sign of a problem. That gives you a chance to find out what the problem is without risking your other rabbits' health.
How long have you had this doe? Is the discharge clear, white, yellowish or green? Are there matted spots on her forelegs where she has been wiping her nose?
Has anything changed in the rabbitry that might trigger an allergy? Things such as: new hay, new bedding or material in the dropping trays, a new bag of feed with a lot of fines, new cleaner, air freshener, perfume, aftershave, unusually bad air pollution etc. etc.
Generally speaking, if the discharge is clear give the rabbit a bit of time in isolation and see what happens. Remove possible allergy triggers. Observe closely.
If the discharge is thick, white or coloured you might want to cull now. It could be snuffles or some other respiratory disease. Hard to treat successfully and a definite danger to the other rabbits.