There is no other reason, especially if you did the test three times? I work with drug tests every day all day and I’ve heard it all before. They cannot touch a drug and then test positive, they can’t be laced or any other excuse because they measure the quantity and there has to be enough in the system to measure, so it would mean more than traces consumed.
Interesting if the test was inconclusive, which could imply something iffy with the test but it was positive which indicates he has used drugs in whatever came back pos.
Maybe his upset is guilt. Sorry