AM3352 connected to Micron DDR3 running at 1.5V with VTT termination has low amplitude signals on address lines

I am designing a control board with an AM3352 processor connected to MT41K128M16JT-125XIT:K DDR3 SDRAM and using VTT termination on the address and control lines. DDR interface is running at 1.5V. The address and control signals only have a 660mV amplitude centered about the VTT voltage of 750mV. The data signals have full 1.5V swing. Is this normal for this MPU? I am concerned about margins on these signals since the amplitude is so low. All 8 boards of a build lot seem to have this issue. I am seeing some strange behavior on several of the boards doing a partial boot, or working then not working and I'm wondering if this has something to do with the signal amplitude on the address and clk lines.