osTicket v1.10 (stable) and Maintenance Release v1.9.15 are now available! Go get it now
I think I misunderstood OSt approach to the subject....
When I pick SLA (48 hours) and Assign a due date, lets say 5/16/204, I assumed that ticket will become overdue on 5/18/2014.
Or SLA is a time for the 1st reply/assignment for a new ticket?