Muscles Stiff After Waking Up?

dwightdegroff

I started doing Insanity about 4 weeks ago(6 days a week) and have noticed this week that my muscles(legs, mostly) are quite stiff when I wake up in the mornings. They're not sore or achy, it just seems like it takes them longer than usual to "limber up".

So a couple questions:
1. Is this "normal"?
2. Is there anything I can do to keep it from happening?

Thanks for your time.