Oh, removing .matplotlib/matplotlibrc solved this issue.
The content of matplotlibrc was really simple, though:
···
--
font.size : 8.0
#
# The figure subplot parameters. All dimensions are fraction of the
# figure width or height
#
#figure.subplot.left : 0.125 # the left side of the subplots of the figure
#figure.subplot.right : 0.9 # the right side of the subplots of the figure
#figure.subplot.bottom : 0.1 # the bottom of the subplots of the figure
#figure.subplot.top : 0.9 # the top of the subplots of the figure
#figure.subplot.wspace : 0.2 # the amount of width reserved for
blank space between subplots
#figure.subplot.hspace : 0.2 # the amount of height reserved for
white space between subplots
figure.subplot.hspace : 0.3 # the amount of height reserved for
white space between subplots
--
Regards