On Friday, May 1, 2015 at 11:13:38 PM UTC-4, Bob Whelan wrote:
The O.P.'s point was he'd tried to signal a U.S. towpilot to
turn a certain direction and was ignored. THAT - by far - is the most
common/likely effect from an ignored or not understood turn signal from a
glider moving off to one side.

this OP thanks you for bringing this full circle. and from a few towpilots' responses, my experience is borne out: some certainly don't pay attention to glider signals, except the tailwag on the ground and wingrock in the air.