why the date exceed the max value of bounds

[Seamless2014]

http://66.18.231.40/heatmap/crv2/drawCharts_MulComparison_download_v1.html?c=Q1JFQiUyMEFyZWE=&m=MTk=&tk=&sc=MTAwMTQsMTAwMTksMTAwMTN8MTAwOTAs&tp=Y3JlYkFyZWE=&istp=MA==&vtmark=MA==&slc=Mg==&sLb=MQ==&cd=&sl=MQ==&sT=MQ==&t=MTI=&ystats=Mg==&pc=MA==&wd=NzEw&ht=MzQ1

These is the link that i use, now the max date is 11/2014(nov 2014),but i can drag the slider or click the right arrow ,make the date to 12/2014(Dec 2014),I think this is a bug, if in the bounds i set the min and max value, the date should not exceed the limit.