First, generally speaking, your groups are much better than norm which is making it harder.
Do you find any pressure signs at 45.1? If not, I am curious to see what next few .3 grains loads show.
Personally, I find it much easier to read when ALL shots are on same line. Moving around adds a variable making it harder to track each group's CENTER and direction. As tight as you are shooting you can easily place five to six groups per line. First thought I had was make 4 to 5 shot groups. But taking Load Development out to 200 or 300 yards should answer your questions.
Lastly, I number each shot (1, 2, & 3) to help me read results when I begin analyzing groups.
Just my two cents...
Extra one cent:
Thinking back my .308 4064 displayed similar results though your groups are tighter for sure. It has been about three years since but off top of my head I found two nodes between ~39.0 to ~43.5. You just may have two nodes in there as well. I still think longer distance will answer your question.
Good shooting