Where did the bolt go off my Counterparts album cover?

I have Rush's album "Counterparts", It's been on a shelf with lots of
other CDs for a few years now (so there's no chance of the cover
fading) and I got it out recently. I could swear there was a nut and
bolt on the front? Now all I see is a black black square?
I looked up the album art on the internet and its a blue cover with a
black square and a bolt in it, but my cover doesn't have a bolt in the
black square. I've inspected the black square thoroughly and there is
absolutely no way the bolt has just faded, there's absolutely no trace
of it - it's as if there was never a bolt there!

Was there a bolt there or are there different versions of the cover,
and if there was a bolt on the cover, has this happened to anybody
else?