Yellowing on sides of fan leaves

Sup guys, this might not be a problem but since its my first grow i would rather be safe than sorry. The first pic is one of my plants and its only yellowing on that one leaf. The other pic is another plant but this one has a couple tiny brown spots on about 3 or 4 fan leaves. Any ideas of what it may be if anything? Also heres what im using

Soil : Fox Farm OF
PH : 6.0-6.5
Nutes : None used since transplant about 2-3 weeks ago
Light/Schedule : 600w MH for veg / 20-4
Watering Schedule : about 2-3 times a week
Stage of growth : Veg for about a month and a week

Early nute burn ...flush with air temp water 3 times the volume of the pot allow to drain in dim light or overnight, see it as a rain storm to wash excess nutes away form the roots

Alright. Really appreciate it. 1 more question. They havent had nutes in almost a month, just wondering how it could be nute burn?

Its not nute burn...you splashed nutrients on them and it burned them (whenever you fed last) or its just plain water droplets left on the leaves burning

Alright. Im guessing the best solution is just to flush it ?