No, but it's not part of words that are indexed by default
(punctuation isn't usually search for, this keeps the index smaller and
more efficient). Thus this query cannot be completely resolved with
the index, and a direct search of data is needed (post-processing).
Since this can potentially slow a high-use server down, it is
disallowed by default.
There's no need, but you can include it in the index expression and
re-index the database, so that it can be resolved. Do gw -unindex
then gw -k"[\alnum/]{2,99}" -index. If other punctuation will be
searched for, include that in the index expression as well. See
http://www.thunderstone.com/gw25man/node40.html.
-Kai