stupid question?

Danielle
Ok this might sound stupid  but I'm a FTM to be and I read an article that hearing the heartbeat early during an internal exam could be harmful to the fetus due to the sound waves used in order to hear it??? 
Is that true?? I heard and saw my babies heart beat at exactly 6 weeks a little over a week ago, and now I'm FREAKING out that hearing it might have been too early to do so and that I may have potentially harmed the baby? 
Am I being ridiculous? 😰 Shouldn't the ultrasound tech have told me that if that were the case? I'm just not sure what to think right now.