releaved & worried

I went to my anatomy scan & I was happy as could be to find out I didn't not have complete placenta previa like I did with my first pregnancy my baby girl was born at 32 weeks weighing 3 lbs but very healthy thank God! so I was cleared for placenta previa but I have another appointment because the ultrasound tech didn't get enough shots of the babies heart or something like that ? the doc came in & told me from what she had seen she wasn't concerned but wanted me to go back in 4 weeks for another ultrasound should I be worried ... I feel like the doc just said she wasnt concerned so I wouldn't worry ? idk