Positive blood test but doc wants me to go back in one week

I got positive pregnancy test. Went in the same day for blood work. Next day, nurse told me it was positive. Scheduled first prenatal visit a month out. 30 mins later the nurse called me back and said they want me to come in next week to do one more blood test because it's very early. Is this normal? I guess I'm still in shock and it's taking me a second to realize this could be real.

( aug 16 was first day of last period. Tested positive exactly 30 days later on sept 14)