I've had my Mavic since Feb and I have over 100 flights not one incident. I think most people that have problems tend to be vocal about it and post on the forum. Most Mavic owners have no issues.
I had this problem when I first started flying my Mavic out of the box. I was able to fix it by calibrating the IMU and the compass. Believe it or not the compass is the cause for most GPS signal loss.
Don't let people annoy you man. **** happens I wouldn't stress about it too hard since amazon is sending you a brand new one. I've flown over water many times without any issues..