yuck - why is that?

Have you ever noticed that every once and a while you will find yourself writing with a really smelly sharpie? I write with sharpies a lot in my line of work, and usually the smell does not bother me because it rarely lingers. Today, however, I wrote with a sharpie and the page with the markings still has the strong and distinct aroma of yucky permanent marker smell. It's been a half an hour since I wrote with the marker! Why is that?