Change in back button behavior

We are upgrading from ColdFusion 9 to ColdFusion 11.  We noticed a change in back button behavior.  On pages running CF 9 the back button works, but on pages running CF 11, when clicking the back button, we get a browser "confirm form resubmission" message.  Since it is the same browser, it is clearly a change in ColdFusion.  Does anyone know when the change was made?  Is there a setting that controls the behavior?

Thank you,

David