I disagree in that all specimen should be treated upon obtaining. I have 3 Mags and 1 Gig. None have been treated with Cipro and all are thriving. That being said, should I wish to obtain another, I would make certain I had Cipro on hand if necessary. I just wouldn't treat automatically.
First, you're right. Apologies for the blanket statement. I guess my point is that most gigs and mags that are freshly imported are sick, and though their outward appearance looks good, unless quickly treated, they will surely die. Cipro has been the only treatment that we know of with a high enough success rating to actually deem it as a cure for shipping ailments.
Second, consider yourself EXTREMELY lucky. I've been keeping a mental tally of mags and gigs that have appeared on the boards, and I'd say that prior to Cipro, 90%+ didn't make it past the first month. Once people started using Cipro, this number has declined DRAMATICALLY.
About a year ago, gigs started appearing that were severely bleached, but were making it through the first month without problems and without any treatment. I think you were one of the people who picked up a bleached gig.
Because of this, I started to think that there was a correlation with the dead zoax and the death of the non-bleached gigs. It could be that what was killing the zoax (some sort of bacterial infection) was also killing the nem. Or, it could be that the dead zoax was indirectly killing the nem (possibly decaying within the nem? Who knows.). The scenario was always the same: initially, they looked decent -- good enough to actually purchase, but they started to quickly decline in health at about week three. I saw this with both gigs and mags. However, the bleached gigs weren't affected (I don't remember bleached mags). I hypothesized that since the gigs made it through the bleaching process, they didn't have enough zoax to get infected to then kill the nem.
Anyway, this is the reason I recommended all gigs and mags get treated -- because I no longer see the bleached ones coming in. But again, you're right -- all imported gigs and mags do not need to be treated. The trick is to be able to tell the signs of a sick gig or mag at the onset. If treated too late, the nem won't make it.