The Quartus® II software version 9.1 and 9.1SP1 fitter algorithm places the resynchronization registers well into the core as opposed to the dedicated I/O element in the periphery causing possible intermittent data corruption on the last word in a burst. There will be no timing violations in the design since Postamble Analysis is not reported by Quartus II software static timing analysis.
If you are using Quartus II software and IP version 9.1, 9.1SP1 in Arria® II GX with ALTMEMPHY for DDR SDRAM, DDR2 SDRAM and DDR3 SDRAM High Performance controller you should upgrade to Quartus II software version 9.1SP2.