Once when I was an immunology lab tech I had a bad week, with my serum, one of the controls, coming out quite positive. Natch that was a week of non-reports and a lot of phone calls because of the change and strange reading, but I still zoomed into despond (waves at Izzie, who has dealt with all of this for real). We always eagle eyed our controls, as various matters can affect test results. That had something to do with pH or maybe the conjugate. The md's ordered a test a second time back then in any case. Still, I stared hard and long at every slide. No one ever rushed me.