weird pickup corrosion

After 6 months of procrastination for a million reasons, I just bought a new neck pickup for my ES-335 yesterday and I've been spending most of the day remembering how much fun this guitar is. I recalled that when I took it apart in summer, both pickups had odd corrosion on the top surface at the high E end. I don't have corrosive sweat, no one else has played my guitars and I've owned my 3 Gibsons for a very long time and never seen this before. I carefully polished the marks away and the remaining, old bridge pickup looks OK. I play the LP all the time but really stupidly, I didn't think to check my ES-Artist back in summer when I noted the problem with the ES-335. Playing the ES-335 all day made me think about the other and I pulled it out of the case to find the same weird corrosion on both pups, same place but much worse, I could feel the rust. Gold pups too.... After several hours, the pups look OK but don't have any gold left on the top surface; most of this was worn off already. It's laid out on the kitchen countertop waiting for more painters tape so I can polish the frets tomorrow.

Back to the problem; any one else experienced corrosion like this? It's got to be from finger contact with the lower edge of the pups while playing but as stated, I've owned these guitars a long time and this has never happened before. Maybe my body acidity has changed as I'm getting older though I don't seem to be noticing any string problems with the guitars I play more often.

I contemplated getting new gold covers for the ES-Artist but the pickups are rare, low impedance types and look like they are sealed with a black plastic goop. The two blobs of solder typical for our pups are not present.

Anyhow, I guess this is a reminder to all that when you are putting away a guitar for any length of time, clean the pickups and other metal work first.

I wipe my guitars down with a cotton rag and let them dry before closing the case. I might toss them in the car after a quick wipe down but do a more thorough job when I get home and leave the case open for a while. And I still get tarnish on the TP post and the PU covers after a few months. But not what you describe.

What's really odd about this is that I travel a lot and there have been a number of times I have left my Gibsons in their cases for extended periods; never seen anything like this before. Frets are polished, it's restrung with 0.008" - 0.038" and it's so fast.

On a side note, I don't know why, but this guitar has always been so easy to set-up with super low action with no buzzing. Set-up is not rocket science; I always do my own but for some reason, this one plays with no effort at all. My LP, ES-335 and EBMM Majesty are pretty much identical; tiny neck relief, same gauge strings, very similar action but the ES-Artist is even lower and there's no buzzing. I really love it.