Low heart rate

Has anyone ever experienced a low heart rate (96 or lower) at there first appointment? Some information about my appointment is I went in thinking I was 8 weeks along and she told me I was measuring right at 6 weeks. They seemed concerned and want to bring me back this upcoming week to check the heart rate again. I know that it is low and she told me they would like it to be 110 or higher. If you have had this happen, please share your experience with me. I have had two previous pregnancies with no problems but I have also never been to the doctor this early with the other two. Thanks!