Hcg didn't double in 48 hours

Desiree
I'm 5w5d and I had my first draw on 3/20 and my hcg was 3583 and my progesterone was 14.94.... I had my second draw today (3/22) almost exactly 48 hours later and now it's at 6331 and my progesterone is 26.36.... anyone else have a similar situation? Nurse didn't seem concerned and said things look fine but I have just hear about the 48 hour rule. Thanks ladies!