Last week I took a friend for a ride in my Sonata. I turned on the radio and set it on a channel I liked and set the volume. After a while I wanted to change the channel but it wouldn't change. I tried to lower the volume, turn it off, switch to am, fm or xm and no control did anything at all. It just remained on the same channel at the same volume. Even when I turned the key off it kept playing.

When we got home my friend took his phone out of his pocket and it was playing the same tune that I had on the radio. He turned his phone off and my radio started working properly again.

When he turned his phone back on the radio continued to work properly and even though we tried to re-create the scenario we couldn't duplicate it.

Could anyone tell me what happened? It was like something out of Twilight Zone.