High HCG/4000 at 4wks

Okay...althought the doctor told me via the nurse that my levels are fine, 4000 hcg at 4wks seems REALLY high compared to all that I have read in the internet.  

11 dpo- 32
17 dpo- 900
20 dpo- 4000

Has anyone had levels like this?  My mother and my Grandma both lost twins so I know a multiple pregnancy is a possibility.  My levels weren't tested in my first pregnancy so I don't know if I tend to run high normally.   Should I be concerned even though the doctors office claims normal levels for 4-5 weeks are 1,000-50,000? (That's a little broad for my comfort...)