Ultrasound at 8 weeks?

I did my blood work yesterday and the nurse called this morning to let me know that everything looked good. Then, she said the doc wants me in for an ultrasound next week. I'm just 7 weeks today. Now I'm paranoid that she was just being upbeat about the blood work so I wouldn't panic, but that maybe something was wrong. I did have an MC over the summer which doc knows about - could that be why? Anyone else have this happen?