I can't speak for how pg feels, but that is a very different kettle of fish.
In your case, you'd have been modifying and distributing his content, rather than providing users a tool for consuming content they have obtained directly from pg.
Think hosting mirrored ad free sites vs creating AdBlock.
He might still have a problem with this (if only because of server load), and it would have been a good idea to check first, but your experience isn't evidence one way or another.
edit: just checked my email, i actually asked him about putting up the epub, not the script. but same difference I suppose.