Oscar scan questions

Hi, I did my first trimester screening today, which I believe is the Oscar scan. During the scan, the technician was incredibly rude and unprofessional. I shall not go into it. But I noticed that during the scan, she did this thermal looking thing and the bar on the left turn all red. Because of her lack of professionalism, I am getting worried about what she did. Because this happened when I was alone with her. And she didn’t do it again when my husband came in later. Hope anyone can shed some light on this. Thank you.