Just passing this along in case anyone else ran into this problem:
I recently upgraded to the latest obspy using the Anaconda installer (on Mac OS 10.10.5)
This also upgraded matplotlib.
The only issue I encountered was a new warning message displayed every time
I ran an obspy script:
/usr/local/anaconda/lib/python2.7/site-packages/matplotlib/font_manager.py:273: UserWarning: Matplotlib is building the font cache using fc-list. This may take a moment.
The solution turned out to be to remove ~/.matplotlib/fontList.cache - I guess the old version is not compatible with the new.
Other than that, the upgrade was smooth.