C.V.
I think it's completely normal for toddlers to express their need to control their own environment in ways that might seem a little obsessive. I know of many kids, my own included, who do things like line up their toys a certain way or who freak out if their hands are dirty. They are learning that they can make decisions about their own world, and exercising that power (which I think is perfectly healthy). My oldest is a "clean bean" - she hates to get dirty. Her little sister, however, has shown her that sitting in mud puddles can be a lot of fun... I think this is a good balance for her.
Anyway, you might want to think of ways to let your little one have more control in her own life. Give her choices and decisions (ask yourself, "why not?") and see if that helps her feel more secure and empowered.