Well, gwonya, in the first post you said any anecdotes would be appreciated, so here goes.

A few years ago, the Kansas City Symphony Orchestra decided to loosen up, and they had a banjo player (I believe it was Tony Triska) perform with them.

The young woman in front of me decided to impress her date with her joie de vivre and commenced to bob and swing her head around in time to the banjo. It wasn't long before I began to feel motion sick as a result. I tried closing my eyes, but that can't be done long with contact lenses. Also, at the Symphony, the risk of falling asleep is great.

So the person who said they felt nauseated may have been perfectly straightforward. He/she may also have loved the sound of your playing, as well. As ddw said, there's nothing to be done except not to watch.