"Flash message" banners for checkout persons

When a checkout person clicks "finalize reservation" they are directed to the check in/out screen (ex: http://ulua.its.yale.edu/stc-loaners/reservations/manage/5).

After this redirect, there should be a message at the top which says something like:
"Equipment has not been checked out yet, only the reservation has been created. If the patron is simultaneously picking up the equipment, it must be checked out below."