Not dumb at all. Ive had some grows go perfectly without ph'ing a thing...then I've had the opposite, leaves discoloring all over the place unexplainable, generally an unhappy plant that i couldn't find the problem, until i double checked my ph pen only to find id be watering with like 8-9 ph which is way too high.
If you don't have it already, get a ph pen, a bottle of ph up and ph down(or powders), and some extra calibration powder or liquids and see if you get any difference on the #s.