I'm not sure if it's just my system, but this figure size doesn't seem to be correct for  the labels you have displayed:
![peak_example](https://cloud.githubusercontent.com/assets/133031/2537419/48e6e860-b5b0-11e3-9b29-b6eb60d58b6f.png)

A bit more height and smaller title fonts would look better. Also, adding a call to `plt.tight_layout()` right before `plt.show()` couldn't hurt.