Yes. Why wouldn't it be? Some kids crawl earlier. Some kids crawl later. Some never crawl at all. She is actually about average for kids that do crawl. Crawling isn't a milestone that doctors look for.
If you haven't done so yet, get down on your hands and knees and take a long tour of your home. What can you reach that she shouldn't? What dangerous things are under your normal eye level? Baby proof, baby proof, baby proof. She will be walking before you know it and escaping your direct supervision in the blink of an eye.
Check out the milestone charts at BabyCenter.com... http://www.babycenter.com/0_milestone-chart-7-to-12-months_1496587.bc
at 11:19 PM on Dec. 26, 2008