The Hub

I just had something happen that I can't understand, and I am looking for theories. I was working on an '80s Kramer. The action could not be lowered any further than about 5/64" -- as in no further downward adjustment in the Floyd Rose -- so I removed the neck in case there was a shim in there. There was not. I put the neck back on and the action was now considerably higher. So off with the neck again, and I noticed the imprint of a coin. I didn't hear anything fall out when I had removed the neck previously, but I searched high and low just in case. No coin, no picks, no shims. I ended up using a fairly thick shim in order to change the neck angle enough to get to 4/64" action.

So, other than a vanishing coin, the only thing I can think of is that the neck heel had been held up over the area where that coin imprint is, and when the screws were put in, there was a gap between the neck and the bottom of the pocket. The legendary "air-shim." Any other ideas?