I am 37 weeks pregnant, my son is measuring at 39 weeks. I recently found out that I have more fluid…

I am 37 weeks pregnant, my son is measuring at 39 weeks. I recently found out that I have more fluid than I'm suppose to (normal is 24-25 & I have 27) I have to have a "non-stress test done. Is this normal or has anyone else experienced this or know anything about this? I'm worried because they say it's uncommon and would like any information, please!