Since it's not a problem that has come up on any model I've ever flown including a 4 ft span biplane I'm going to fall back on my previous suggestion that tis is a freak occurace for this one particular design. Something about the overall setup and the air off the wings is "packing up" under the stabilizer and forcing the nose down. If the air off the wings is diverted by the ground effect and alters the apparent angle of attack of the stabilizer then yeah, it could push the nose down and resulte in these "arrivals".

But I stress that this is not the case for the vast majority of designs and not something I've ever seen.