Nope this is an example to clarify why I made this ruling. Would you make the spell just appear in the spell book. The wizard does not have any ink, not even a feather write with. So how does the spells appear? I am curious about the mechanic of spell writting itself in a spell book.
To paraphrase Oofta: Free of charge, not of copying.
You do realize he was criticizing your ruling not agreeing with it?
And what about the side bar? It does not say:"Except those you had free from leveling."
Like Oofta said. Free of charge, but not of shipping.
"On your adventures, you might find other spells that you can add to your spellbook (see the "Your Spellbook" sidebar)." In the sidebar it first mentions spells you research on your own, not mentioning any cost. It then talks about other spells you find as distinct from spells you gather on your own (as in spells someone else researched that you find. The cost of copying is as to those spells.
I find both passages clear, it is certainly not clear that it is the other way around and that you have to pay for spells you get with level.