HCG levels 4 weeks 3 days

Hi ladies! I had my hcg levels done at 4 weeks 1 day and it was 500. At 4 weeks 3 days I was retested and it was 1600 then! The obgyn was happy about my results. I miscarried before and am a worry wart! It seems like the levels tripled! I'm worried about a molar pregnancy. Did anyone else have their HCG levels triple?