Tan-lines on your hands?

Every summer they seem to show up.  Those weird tan-lines that aren't from the tightly hugging bib-shorts but those generated from cycling gloves.  To be fair, I'm sure any "gloved-sport" has the same weirdness pop up but I keep forgetting about them when winter roles around.  It's a whole new sense of surprise when the normal bicep farmer's tan-line gets a new friend on the wrist.  Maybe the real answer is to wear more sunblock...or get a better tan all around...