https://bugs.freedesktop.org/show_bug.cgi?id=60182
--- Comment #34 from Michel Dänzer michel@daenzer.net --- (In reply to comment #33)
(which AFAIK is normal, but didn't happen before).
Yes, that's normal and not related to this problem.
Note that the 'Attempted to destroy previously destroyed buffer.' messages would appear in the Xorg / LightDM log files, not in the terminal where you run the application.