Apples may not have always grown from nowhere, but extraordinary events have frequently occurred him around you, extraordinary even for a ta'averen! I'm sure you recall the events that occurred in his wake as he fled his companions during The Great Hunt. However, up until this book, his over all "side" was still in limbo. There was still the potential for him to become allied with the Dark One. So all of these events were balanced. Some good, some bad, some just kind of random without any particular alignment. At this point in the series, though, he has placed himself solidly in the camp of the Creator. His ta'averen energies now have a single specific "good" direction, so more good things happen. This apple event actually has a very strong Arthurian influence. When Arthur was ill and dying, the land died around him. However when he was revived to health by the Holy Grail, the earth sprang back into life. This parallel has actually run pretty consistently throughout the series. This apple event is just kind of blatant.