It is more than one isolated case. I would venture to guess that it is the reason for the discontinuing of the EII series. The problem is in the type of rubber used, how the surfaces are prepared before applying the glue, and the type of glue used.
The rubber seems to have a very stable composition, and does not accept easy contact and "melt" with glues. It also has an extremely smooth surface, which is not conducive to increased contact area between rubber and glue and metal.
The glue used is just an "el cheapo" kind, sensitive to temperature changes.
The metal surface is very smooth anodized AlMg alloy. Because of its smooth surface, any glue will have a reduced surface to bond to.
I have a pair of 10x35 EII that did not survive a hot New Mexico summer without loss of some rubber. I sent the whole thing back to Nikon, and it was promptly (2 weeks) re-glued. The rubber went loose the very first morning when i went birding again.
At that point i decided to take matters into my own hands. I taped (masking tape) lenses and other surfaces that i did not want to damage.
I peeled all of the remaining rubber. I cleaned, scoured, and scratched the metal surface with acetone, knife, and 180 grit sandpaper. After this operation, most of the metal surface was clean, exposed, rough looking metal.
I also used sandpaper to roughen the surface of the rubber.
I cleaned everything with a alcohol and cotton.
I used Acraglas gel mixed with atomized aluminum, and smeared this goo on the rubber with Qtips (cotton tipped sticks).
I placed the rubber in the right place.
This process was slow and careful. I worked in 6 phases, because i could not glue the rubber on one side and then move on and handle the binoculars and glue on the other side. It was a 3 day process.
I had cotton balls with vinegar and with alcohol to clean any excess Acraglas. Being a gel, it only oozed a little at the edges of the rubber.
It turned out unbelievably well (whenever I start projects like this I assume complete screw-up responsibility). The binoculars had a weird smell for a few days, but it’s ok now. The rubber is so solid that it will take a bullet to get it off the metal. Upon close examination, there are absolutely no visible signs that any repair has ever been done. To test my work, I kept the binoculars in a freezer at -10 Celsius over night, and in an oven at +45 Celsius for 2 days. The rubber is all there, tough as nails, and the binoculars are solid like a rock.
I believe that the 8x30 and 10x35 EII binoculars are so good, that the engineering flaw of bad rubber cover is just a minor thing.
Acraglas is an epoxy resin commonly used in custom/high grade rifles to ensure proper fit between stocks and metal.
http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=1038
Try this at your own risk.