These songs are actually written/performed by lead guitarist Neal Casal. They've been setlist staples for awhile and are on his album No Wish to Reminisce which came out a year or two ago.
And yeah, the new songs are outstanding. "Cobwebs" might be one of the best things he's ever written, "Fix It" gives off a great Dead vibe, and "Magick" just fucking rocks.
I'm still insanely jealous, I have to wait another month to see them.