Band was joined by the legend and his two sons for a play through of “I’m Blue I’m Lonesome” at last night.

Earlier in the day the festival photographer snapped this shot…

©

So it was really no major surprise when we saw this one to follow it up soon after…

View this post on Instagram

Del and the boys sitting in with Trey.

A post shared by DelFest (@delfest) on

Check out the video clip below and stay on for the great Trey solo.

Band w/ "I'm Blue and I'm Lonesome Too" Delfest, Cumberland, MD 05.26.17

[via]