Henry was placed on the 7-day minor-league injured list with an undisclosed injury Thursday, Jesse Dougherty of The Washington Post reports.
Henry has made two starts since being promoted to Triple-A Rochester and has posted a 4.50 ERA and 1.38 WHIP in eight innings. He hasn't pitched since June 11, and it's not yet clear how long he'll be sidelined after being placed on the IL.