Can we see a photo of what you're talking about? A lavender should be all over much more lavender in hue, including bands. If you're wondering what a lavender should look like, you can go see the gorgeous lavenders at JMG Reptile (They have the best I've ever seen), here is a link: http://www.jmgreptile.com/lavenderstripes.html
Its odd though because it is a small spot on each horizontal band of the gecko. It was not like that when I first got it btw. Its hard getting a good picture of it.
JMG definitely has some nice stuff and I've looked high and low for some good quality lavenders for sale. I will have to add a male from them before next year. Thanks for the lead.