Actually I give a great deal of credit to Van Dorn for keeping his column together and taking them so far east to avoid detection. I believe it would have been a major gaffe on his part to have sent out a screening force. The presence of such a body would have been an indication of something happening in the theatre that needed screening.
I have not seen anything written by participants to indicate one of the three brigades was off on a mission to screen the column. There are plenty of diaries, journals, memoirs, articles written by the participants and they are representative of the three brigades under Jackson, Griffith and McCulloch, none of them however, mention being on a ride on that road or in that neighborhood.
Van Dorn is not remembered for devising elaborate plans of battle, but on this occasion he successfully pulled a division out of the line and in a sweeping movement to the east, stole a march on Grant that was not discovered until he was moving beyond Pontotoc. Van Dorn at the top of his game!

Tom