Crawling Baby Napping More

My daughter is about to turn nine months old and is crawling a lot more now since we opened up her play pen to give her more free roam. She is also pulling to stand a lot and trying to stand in her own. With all this being said she has been napping a lot more than usual and for longer periods of time. Is this normal? Could she be teething again? Or a growth spurt? I'm a FTM and just don't know. Thanks in advance for any advice.

Picture to get attention. Lol