I would have to agree with you. I have 16 S3's and 1 S4 at the moment. 4 more S4's are on the way.
I did notice something that caught my eye when you said, "no X's"
I know this is an S4 forum, but one of my S3's has a dash at the end of the zeros. what does that mean? "00000000-0000000-"
Not sure actually. X non-responsive? - dead. Just a guess. But a hard reset usually does the trick.
A simple reboot did not work.
I had to do a hard reset like you said and the dash at the end of the zero's is gone.
Thank you!