Spoke in Navajo without knowing what it was

My church's deacon Bob O told this story about 10 years ago.  Bob is considered a very Godly person and would never make this up.  Before Bob and his wife Kathy had children, they spent some time doing mission work on a Navajo reservation out west.  In the months preceding the trip, they did a lot of praying, and had a strange event happen:  Bob felt the urge to pray "in tongues" (yes, that's strange to me too... but keep reading).  He spoke the same thing at several points in time, so he wrote down the sounds on paper and kept them with him.  He asked some people if they understood it, and they said no. 

God encountered at Navajo Reservation

A few months later, after they had been on the Navajo reservation for a while, Bob was sharing this story with one of the Navajo leaders, and the leader did not dismiss him.  He asked to hear the sounds, which Bob promptly repeated.  The Navajo leader surprised Bob by saying that it was perfect Navajo language and that it was a message praising God.  (!)