Possible Bug in alignment of mathtext in axis tick labels on OSX Mountain Lion

OS: OSX 10.8.5 (Mountain Lion)
Matplotlib Version: 1.3.1
ipython: 2.1.0
gcc info:
Configured with: --prefix=/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin12.5.0
Thread model: posix

Matplotlib Obtained: Installed via pip, auto chosen options below

BUILDING MATPLOTLIB
                matplotlib: yes [1.3.1]
                    python: yes [2.7.6 (default, Jan 28 2014, 11:09:35) [GCC
                            4.2.1 Compatible Apple LLVM 5.0 (clang-500.2.79)]]
                  platform: yes [darwin]

    REQUIRED DEPENDENCIES AND EXTENSIONS
                     numpy: yes [version 1.8.1]
                  dateutil: yes [using dateutil version 2.2]
                   tornado: yes [using tornado version 4.0]
                 pyparsing: yes [using pyparsing version 2.0.2]
                     pycxx: yes [Couldn't import. Using local copy.]
                    libagg: yes [pkg-config information for 'libagg' could not
                            be found. Using local copy.]
                  freetype: yes [version 17.2.11]
                       png: yes [version 1.6.12]

    OPTIONAL SUBPACKAGES
               sample_data: yes [installing]
                  toolkits: yes [installing]
                     tests: yes [using nose version 1.3.3]

    OPTIONAL BACKEND EXTENSIONS
                    macosx: yes [installing, darwin]
                    qt4agg: no [PyQt4 not found]
                   gtk3agg: no [Requires pygobject to be installed.]
                 gtk3cairo: no [Requires cairo to be installed.]
                    gtkagg: no [Requires pygtk]
                     tkagg: yes [installing, version 81008]
                     wxagg: no [requires wxPython]
                       gtk: no [Requires pygtk]
                       agg: yes [installing]
                     cairo: no [cairo not found]
                 windowing: no [Microsoft Windows only]

    OPTIONAL LATEX DEPENDENCIES
                    dvipng: yes [version 1.14]
               ghostscript: yes [version 9.07]
                     latex: yes [version 3.1415926]
                   pdftops: no

Problem:

Using the default mathtext renderer, axis labels overlap the spine.
Pictures of the problem are available at
http://stackoverflow.com/questions/24997386/latex-tick-label-overlapping-axis-in-graph-generated-by-matplotlib/24999963#24999963.
Turning on tex rendering via rc('text', usetex=True), makes the
problem go away which indicates this is a possible bug in mathtext (or
perhaps the libraries used by it on OSX) and I thought I should report
it.

Minimal Code Producing Error:

from pylab import *

xticks([-np.pi, -np.pi/2, 0, np.pi/2, np.pi],
       [r'$-\pi$', r'$-\frac{\pi}{2}$',r'$0$', r'$\frac{\pi}{2}$',r'$+\pi$'])

show(block=False)

Extra Potential Relevant Information:

When calling verbose-debug, there are a bunch of lines like this one:

Using fontManager instance from /Users/wd239/.matplotlib/fontList.cache
backend MacOSX version unknown

findfont: Matching
:family=sans-serif:style=normal:variant=normal:weight=normal:stretch=normal:size=medium
to Bitstream Vera Sans
(/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/mpl-data/fonts/ttf/Vera.ttf)
with score of 0.000000
findfont: Matching
:family=STIXGeneral:style=normal:variant=normal:weight=normal:stretch=normal:size=12
to STIXGeneral (/usr/local/Cellar/python/2.7.6/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/matplotlib/mpl-data/fonts/ttf/STIXGeneral.ttf)
with score of 0.000000
......