The Coordinated Strike (melee version) from the Falconry enhancement tree is not applying Assassinate bonuses to the DC.
While you're looking at this would it be possible for the Summon Falcon stance to NOT get turned off on death. It's just one more thing to have to take care of after being rezzed if you go down in battle. I can handle it being defaulted to "off" on log-in but it's a PITA to turn stuff back on after you die.