We are in the same boat. I traveled many times last year coast to coast as well as to Hawaii. United was my carrier and were fantastic. On one occasion a male who was with 2 other males with middle eastern characteristics went to the bathroom a few times during our flight to the west coast.
5 minutes before our decent he went into the bathroom and NEVER came out, even after I departed the plane. I was on high alert and there was definitely something going on.