The same thing happened to the feet on the pedestal for my HP150B and
it was sitting atop a 9121D like it was meant to. It has also happened
to the feet of several other things as well, all of various ages,
after about four years or so. It seems to happen to a particular
rubbery but very "sticky" material, which they all happen to be made
of, which also stains and is a bit difficult to remove.
--
jd