Orange spots

Hi!
I've got one plant (Jack Herer) that has two leaves with orange spots on the side & tip. She's just over 3 weeks (from seedling). There are 4 total plants in the tent and none of the others have it.

I'm super paranoid of over-watering, so I usually wait till its quite dry before watering (every other day) with pH adjusted water (tap H2O at 9.5 reduced to 5.9-6.0 from lemon juice). Foxfarm nuts (1/4 of recommended dose) every other watering..also pH adjusted.

What in the world is that spot? Do I need to worry?

Thanks!

Kind of looks like a spill? Or do you spray your plant with something?

typically for a deficiency to be that dark in one spot or that big there are usually multiple spots. At least that’s been the case for me. It looks perfect other than that spot.