After my last test drive, I was looking over the new A/F numbers and I am curious about the A/F dip at 3500rpms:

40mph 2200rpms (16"hg) 15.4
50mph 2500rpms (18"hg) 14.6
60mph 3100rpms 14.4
65mph 3300rpms (17"hg)14.4
70mph 3500rpms 13.6
75mph 4000rpms 14.6

Is this A/F dip showing when the main jetting is starting in or is there something else? It seems weird that it takes almost a 1.0 dip in between the 3300rpm and 4000rpm range.
If this is the main jet, should I lean out the main jets by one or two sizes and restest?

Thanks