That's indeed strange Donz, and unfortunately I don't have an answer for you but if it were me, in first instance I think I'd go back to VV and tell them what happened. The chrono reading is the weirdest part of this. If it hadn't been for that, I'd just say take it back another 2 -3 grains and start again but the chrono reading complicates things.

I have certainly had instances where recommended (by manufacturer) minimum loads have proven to be way too hot, the most recent being a .308 where bolt-lift at min loading was difficult to say the least. So yeah, give VV a call and tell them what happened.