Could be overcooked,to the fall apart stage,and be dry.
Starting with choice, is hopefully going to have more internal marbling,and more moisture.
Choice might extend up in quality as much as another rough 30% of the graded meats,until you get to prime.
Each level,hopefully gets better.
Did the meat probe go thru the flat like butter?
Did you check a couple places with a good instaread,to verify temps?[Just for future reference,since temp doesn't equate to tender.]
Did you check the AQ probe for accuracy?
How quick did you serve the meat,after slicing?
Instantly?
Maybe we can help a little,with these answered.