Yes. The leopard sign is a non sequitur meant to further emphasise that this is precisely not the place one would expect to look for the item in question. It could have been a sign about anything but the "Beware of the leopard" is perfectly unrelated to the topic. This is the kind of thing Adams had a real genius for.

My understanding was that the sign was an entirely bogus but rather worrisome warning, put there as a somewhat deceitful tactic to dissuade people from reading the real notices (about demolition, for instance).