Retiring bugs - or - guilty until provent innocent?

[Darryl Rees <rees netnam vn>]

Dear Luis et al,

There are bugs (often build bugs, for eg.) that previously i was able to 
duplicate, but subsequently have not been able to duplicate for several 
months.

Obviously 'works for me now :-)' is not a reasonable premise for 
retiring a bug, but in many cases it feels like these were short-term 
transient bugs and that there's little utility to retaining them as 
unresolved bugs in bugzilla.

Is there anything that can be done to help clean out such bugs; if 
nobody has commented on them for a few months, can somebody add 'haven't 
seen this for a few months now' or something like that?

Cheers,
Darryl Rees.