I heard Baba's spoken stories would sometimes perfectly match the books being read. How did this happen?

Yes, this was considered a great wonder among the devotees in Shirdi. Chapter 18 describes Sai Baba's profound method of teaching and providing confirmation to his followers. On occasion, Baba would tell a devotee a short story while they were with him in the Masjid. Immediately after, he would instruct them to 'get up, go to the Wada for that book.' When the sincere devotee went to where Bapusaheb Jog was conducting the daily reading, they would find that the passage being read from the 'Jnaneshwari' or 'Nath Bhagawat' contained the very same story Baba had just told them. This created a powerful experience, confirming Baba's words and making the scriptures feel like a direct translation of his speech.