I'd be
more concerned with accidentally scratching the
glass bed of the scanner due to sharp component leads.
You can't scratch glass with metal. What you can do is leave
a thin trace of metal on the glass. Gewelers rouge will easily
remove this is nothing else will.
I guess that there is a slight possibility of degrading the
contents of an EPROM if its window isn'tcovered.
Glass is opaque to UV so you won't erase EPROMs either.
EPROMs don't have UV-opaque glass windows, they have
UV-transparent quartz windows. So they can be erased,
but not by casual exposure.
Regards,
-dq