No, I haven't yet. I killed Brian and decided to hold back for a while and mess around with Angus' bike thefts and some other side missions rather than rushing through the story as fast as possible. Thanks for the help
UPDATE: I did Elizabeta's mission with the Uptown Riders and afterwards received a text message from Clay saying he heard that my Hexer got messed up and if I give him a call he'll fix it up and bring it to me. Guessing that should fix the problem.