10-4 on that.In cases where strain deterioration occurs (and while it undoubtedly does, I think it is talked about far more often than it is observed) it is, I am fairly certain, almost solely because of contamination.
I will say I *think* I've seen some strains throw petites (something wrong with the mitochondria), but I've been too lazy to check them on the right media (0.1% glucose and 2% glycerol, IIRC).
Basically, RDWHAHB.