Your plugs are saying they are working!! Lol.
I wouldn't sweat it, you aren't lean which is good, if you haven't had your injectors cleaned and rebuilt, your prolly sticking on the mag side and running little rich..or the ecu programming is running richer on the mag side, which IMO is best cause that side always runs leaner and is the side the breaks first in most cases...
I would be fine leaving as is and cleaning injectors regardless next time your motor is out.
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