Honda Odyssey

Sounds typical of a worn inner cv joint housing but since it's so new I'd have to guess that the mileage is too low for that to be the cause yet. You might consider looking at the engine mounts that set the position of the engine. If it is off-center, one cv joint can bottom out in the housing or the other one could bang up against the retainer ring when the engine rocks under acceleration. Usually you will feel that at any speed however the vibration could be too weak to feel until it matches something in the vehicle that hits its "resonant frequency" which will amplify it and make it easy to feel. Think of the pendulum in a grandfather clock. It takes very little energy to keep the pendulum swinging at its natural frequency, but a lot of energy to make it swing faster or slower.