Tested in Ubuntu 14.04 with Python 2.7.6 and Debian unstable with Python 3.4.3. with Matplotlib default backend (TkAgg). Matplotlib loaded from distro repositories.

The following code should stop after 1 tick but instead continues printing ticks forever:

#!/usr/bin/env python
import matplotlib.pyplot as P
def fn():
  timer.stop()
  print("tick")
fig, ax = P.subplots()
timer = fig.canvas.new_timer(interval=1000)
timer.add_callback(fn)
timer.start()
P.show()

Workaround is to replace "timer.stop()" with
timer.single_shot = True
and that does stop the timer upon execution.

Documentation describing stop() method:
http://matplotlib.org/api/backend_bases_api.html#matplotlib.backend_bases.TimerBase