It's not abnormal. I've had batches of chicks with NO losses, and some with a few... as long as the rest are strong, have bright clear eyes and are peeping around looking strong, it sounds fine.
Sometimes there's just a few that are weak or get stressed. Also, if they get chilly, or just pile up on each other they can smother the ones on the bottom... how many did you get? If you have a lot, it's often better to have no corners where they can squash each other into. (were they found in the corner? under the lamp? near the water?)