The "hated the surface" stuff is often bogus and basically a trainers excuse when they can't find a better excuse.
It's valid when a horse tries a new form of surface - but something was obviously in play other than John Henry not liking the type of dirt on FG's track. His last race at FG and first at KEE seemed to be a very indentical type of performance.
He seemed to turn around greatly in that time frame between April 11th and May 21st.
Here's the video of his turf debut win:
http://www.youtube.com/watch?v=VDoabBz_JhM
His jockey wasn't exactly riding him with great confidence.