[NTG-context] Curious blank page

All, Why is it that the rest of the page after Answers on page 4 of the compiled pdf is blank? %output=pdf \starttext \setupindenting[medium,yes] \setupwhitespace[medium] \chapter{First Chapter} \dorecurse{2}{\input tufte\par} \section{First Section} \dorecurse{5}{\input tufte\par} \section{Exercises} \startcolumns[n=2] \dorecurse{5}{\input tufte\par} \stopcolumns \section{Answers} \startcolumns[n=2] \dorecurse{5}{\input tufte\par} \stopcolumns \section{Second Section} \dorecurse{5}{\input tufte\par} \section{Third Section} \dorecurse{5}{\input tufte\par} \stoptext