After having my coils and plugs replaced and a tune up performed, my 2k GLE Maxima definitely dips/hesitates at exactly 3500rpm (and consistently at 3500rpm) and picks up MORE power after the dip.

Is this normal? If so, what causes it. This didn't happen before the coils and plugs were replaced -- or if it did, it wasn't noiceable. The plugs were in rough shape -- intermittent very rough idle problems at start, overall rough idling. Very smooth idle now. They had 72k miles on them -- previous owner didn't swap them at 60).