Taylor kit is approximately 8 months old. I tested the water via Taylor immediately. At work, there was about a 10 - 15 minute lag time between sampling at my home and testing at work. In both scenarios, equipment, vials, etc are either unused/ new or cleaned thoroughly.

The only other variable might be that I didn't let my sample at work equilibrate long enough, such that the reading wasn't actually stable. I dunno, though.