boonyville

I am new to bloodbank, so forgive this tangent. I recently started working with a few techs schooled in the <outside the USA>.One did not know if her DAT was positive, so she added a drop of saline to the spun mixture ... she then called it "negative". Is there any valid reason to do this???? It seems as if she is convienietly diluting out a weak reaction...OR if it is that weak of a reaction,does any one care? It was a post-tranfusion reaction work-up...