Normal HCG levels in early pregnancy?

My first day of my last period was May 10th, 2011. I got a pretty early positive pregnancy test yesterday (June 5th) and confirmed it at the dr. My urine test was "inconclusive" at the drs, but the blood test said my HCG number was 37. I assume the urine test was "inconclusive" since it was midday (not morning urine) and still SO early. I am roughly 3 1/2 weeks pregnant. The drs are re-checking my blood hcg levels on June 8th-they claim my HCG levels are a little low. My question is, for being only 3 1/2 weeks pregnant (14ish DPO), is a 37 low or normal? Looking online it seems to be pretty normal. I know that in 2 days, when I see the numbers have over doubled (hopefully) that I'll rest assured...but until then-I just want to know that a 37 is normal. Thanks :)