Showing Signs Of Crawling??

I was watching Isabelle playing on her activity mat today and noticed something new that she is doing. When she reaches for her toys now, she's started to plant her face into the floor, lift her butt up in the air, tuck her knees underneath, and kick. She has always kicked furiously when she's on her tummy but this combination of things is very new. She doesn't really get anywhere except the usual rotating on the spot but perhaps it is a sign that she is trying to crawl.