[growse]

I don't remember if this is in the original text, but is there a time constraints on distributing the source on request?

If a user asks for the source, and the distributor says "sure" and then delivers it 12 months later, have they violated the license?

[globular-toast]

It has to be the source of the distribution the user currently has a copy of. So they can't just say "sure" and then wait until the next public release. I'm not sure about timeliness, though.