Are Multiple HCG Tests Normal?

So I had my HCG tested at 10DPO. It was 39, which is normal for how early I tested based on what I read. We had the lab fax the results to my OB’s office and we got a call back from the receptionist saying that my doctor will be in tomorrow and she might want me to get my levels checked again because it’s so early and also because I had a previous miscarriage. Now I’m worried that they think something is wrong. I keep taking pregnancy tests and the positive lines are getting progressively darker, so that must mean my HCG level is rising, right?