Could The Pregnancy After Tubal Ligation Be Ectopic?

I had a tubal ligation 5 years ago. I just found out last week that I am pregnant. My OB said i was approx. 6 weeks along. My question is, is it normal for him not to insist on monitoring my hcg levels and an earlier ultrasound to rule out an ectopic pregnancy? I am worrying myself sick over this.