2nd trimester ultrasound

I had my second trimester ultrasound today. My tech took a really really really long time and she didn't tell me anything other than that the baby is 13oz now and that it looks like a boy. And she also said to get a follow up ultrasound in 4 weeks. The ultrasound took a whole hour. Is this normal? I'm getting concerned. My appointment is on Tuesday. And won't know anything until then and I'm so worried