A rider in front of me complained about my lights today. We were riding over a bridge, at night, I was behind him as he was slow but the bike path at the edge of the bridge was narrow, he had a helmet mirror, probably my lights were flaring in his mirror. I have to remember to be more considerate and shut off my helmet light in times like that.

Here's a pic of the bike's handlebar light (lower) and the helmet light (upper, helmet is set on the garbage can that the bike is leaning on). In real life, the handlebar light is not this annoying as it is pointed down. But if the helmet light is pointed right at you, it is this annoying.