anyone's babies NOT sleeping through he night??

My son is about to be 7 weeks old. He goes down anywhere from 8-9pm and then sleeps a 3-4 hours stretch. But then after that it's a hit or miss how much he will sleep. Sometimes he will go back down for 2 or 3 more hours and sometimes he will be up every hour after the first stretch of sleep. I'm seeing all these stories of moms who's babies are already giving them 8 hours of sleep! My daughter was a very good sleeper, so this is a change. Not that I'm complaining cause waking up to his sweet face makes it all worth it! :) any other Momma's in the same position??