Yup, totally normal. They say that babies this age should sleep 15-18 hours a day, but most babies only 12, which is on the low side. It's good for the development, because a well rested and alert baby is able to aborb more then one who is over tired and cranky.
People always tell me (because I have a reistant napper) that "she'll sleep when she's tired".
If I followed that train of thought she'd only sleep 10 hours a day and NOT nap at all. She rubs her eyes, yawns, and fusses until she finally conks out, and it has been known for me to spend more time getting her to sleep then she spends sleeping, BUT, little babies need to sleep.. even if they fight it.
But I gotta say - TAKE ADVANTAGE OF EVERY MINUTE!! LOL! I would kill for Ava to sleep like that. I only get anything done if I'm wearing her because she will not nap on her own to save my soul these days.