Old clue, but a really very good one:

Kristina Frye is dining with Jane and to show her psychic abilities to him, she reads a waiter and reveals the Alabama football slogan 'Roll Tide' as part of her reading.

Later, when Red John rescues Jane he recites The Tyger to him, and then in telling Jane that Kristina sends her love (i,e, revealing to Jane that he has abducted her) he then taunts Jane with Roll Tide.

There is no way that Kristina tells Red John about the reading of the waiter and what she said to him in that detail. Think about it. She is abducted and terrified no doubt. This is inconceivable. There is only 1 way that RJ knows the Roll Tide connection, and only 1 reason he says it to Jane. He has already told him he has Kristina, so by saying Roll Tide also, it is solely to taunt him that he was listening in on that lunch. Either he was at a nearby table, or more likely, he has Jane under constant surveillance and bugs. His taunt of 'Roll Tide' is to gloat about this surveillance.

Who esle do we know, amongst the 5 remaining suspects, is it factually known to be a master expert of surveillance?