I had pretty much the same shudder from my 2009 pilot. At certain rpms/speeds it would shake like heck. The vibration seemed to happen more often and shake harder over a period of a few months. I talked to a honda tech who suggested changing the trans fluid. That fixed it. His explanation was that the fluid viscosity needs to be right for the torque converter to function properly. As a test, there is a small button on the left side of the gear shift column which takes the vehicle out of overdrive. If you do not notice the vibration while out of overdrive, it may be the trans fluid. I asked him about the lockout solenoid, he said if it was malfunctioning there would be an error code raised by the transmission which they would have seen in the diagnostics. hope this helps.