34 weeks &' doctors found something in my placenta...

So today I went for an ultrasound, I get one every 3-4 weeks due to being high risk , but so far the pregnancy has been amazing butttt one little problem today the doctor found a cyst on my placenta , they told me its nothing major that some pregnant woman get it , that it's normal and baby would be fine  they didn't seem worried not one bit , but I'm still worried about it .. now they want to see me every week to keep an eye on it .. I'm just wondering if anyone else experienced this ??