Doctor requested 6 week ultrasound

Hey ladies! My doctor has had me come in three times for HCG tests and levels have been tripling as hoped. Today the nurse today said the doctor wants to see me for a 6 week ultrasound, even though they originally said they don’t do one until 20 weeks. I’m super excited because this means we get to see our baby extra early! But, I’m slightly nervous because does this indicate anything to be concerned about??

Have any of you done early ultrasounds?? And what was the reason?

Thank you!!

Ps, currently 4 weeks 6 days