Strictly speaking, and not to belabor the point, the GPL states that if you don't provide the source code directly, you must explicitly offer to make it available upon request. Otherwise how is one to know it is even available?

While I'm on the subject, I'm surprised nobody has mentioned the other conditions for distributing copies of GPL programs: namely, retaining copyright notices, statements of warranty, and a copy of the license itself. Debian normally keeps this information organized under /usr/doc.

-v