Rales, no other symptoms

[Fliese]

I have a 1.5 year old easter egger who has raspy breathing (rales). She has no other symptoms. No discharge of any kind, egg production has been fine, activity level is normal, etc. Just the rales. I know many respiratory illnesses result in the surviving bird being a carrier for life. Is that true for all respiratory illnesses or just some? I believe she is the only one in the flock of 30 with rales, and I just noticed it today. Basically, I'm wondering if it's worth spending the money to see if a vet can diagnose her or if all such illnesses should result in culling, so why spend the money. It is worth noting that we have just started hatching out our own chicks from select birds (not the EEs) with the intent to start selling chicks in the next year or two. I don't want to save a bird and then accidentally/unknowingly infect someone else's flock down the line because I didn't know to cull.