Yes, I've always had this experience, even before photoreading.It's normal for me.
It used to worry me somewhat but now my attitude is to let it pass.
What I suggest is just be a witness to it.So your heart is beating faster and louder.Just say to yourself, "ok, that's cool, right let's see what happens"
If you try to ignore it then you won't be able to.
This state usually passes and then I'm as relaxed as I can ever be.
I don't know myself, but maybe it's a sort of transition stage as you go deeper into yourself.
