Getting Dark

I'm new to Leos, and I have a quick question. My Leos have been getting darker over the past 2 weeks. Is this their preshed stage, or am I doing something wrong?

-Marc

Are they adults or babies/juvies? They do change as they grow. Do you know what morphs they are? Some should be darker than others.
Are you keeping them on a dark sand?
What is your set up and temps? They may be too cool, that will cause them to look darker sometimes too.
Can you post pics of them?
They may be getting ready to shed, they do so every couple of weeks. Some get darker then lighter then shed and some just get 'dusty' at the last minute then shed...again, depends on the coloration/morph of the Leo.