Weird scary call, not sure what to think

Angela
Hi
So I am 7w 3d pregnant today.  I had my first doctors appointment yesterday.  I had a blood draw and an initial checkup and was told to make an ultrasound appointment for next week.  We made an appointment for Monday
Today I got a call asking if I could move up the ultrasound to tomorrow.  I asked if everything is ok, and she said they just thought they could see the baby already and could I move it up.  I asked again if I should be worried and she said my progesterone was a little low but I shouldn't be worried.
Just seems weird that something in my blood made them want me to move my ultrasound up 4 days and I shouldn't be worried!!
Anyone have anything like this??  I'm a little freaked out.
(This is my 4th pregnancy, the other 3 were all healthy, and I am overweight but otherwise in perfect health)