Why is a piece of painted furniture still kind of tacky three weeks after being painted?

One of the painters at my job painted a book case for me. It was one of those fake wood-looking things. He said he put two coats of primer on it before the coat of regular paint. Still, three weeks after being painted, things kind of stick to it. I have decorative objects on top of it, and when I pick them up, they are kind of “stuck” and make a little sticky noise when I pick them up. Why would that be? The paint is definitely dry.