--plot is hung

Hi All.
During Hot gym prediction,when I ran --plot , it is showing the plot. However after traversing all rows from the csv files, the script is still running and not coming out/ showing the command prompt.
After a long time i presed cntl-c to come out from the script.

        After 3700 records, 1-step altMAPE=15.767246
        Read 3800 lines...
        After 3800 records, 1-step altMAPE=16.355720
        Read 3900 lines...
        After 3900 records, 1-step altMAPE=16.616973
        Read 4000 lines...
        After 4000 records, 1-step altMAPE=17.161386
        Read 4100 lines...
        After 4100 records, 1-step altMAPE=17.261151
        Read 4200 lines...
        After 4200 records, 1-step altMAPE=17.313022
        Read 4300 lines...
        After 4300 records, 1-step altMAPE=17.336687


        Traceback (most recent call last):
          File "", line 151, in <module>
            runModel(GYM_NAME, plot=plot)
          File "", line 141, in runModel
            runIoThroughNupic(inputData, model, gymName, plot)
          File "", line 133, in runIoThroughNupic
          File "/home/sanjukta/nupic/examples/opf/clients/hotgym/prediction/one_gym/", line 198, in close
          File "/usr/lib/python2.7/dist-packages/matplotlib/", line 244, in show
            return _show(*args, **kw)
          File "/usr/lib/python2.7/dist-packages/matplotlib/", line 192, in __call__
          File "/usr/lib/python2.7/dist-packages/matplotlib/backends/", line 74, in mainloop
          File "/usr/lib/python2.7/lib-tk/", line 417, in mainloop

Any suggestion is welcome.