anything to worry about at start of week 7 flower????

is there anything to worry about with this burn coming on my plants at start of week 7 flower heres a few pics its only one or 2 leaves on 2 of my plants out of 4 so not sure if its lights or nutes

My plants do the same thing and I've not had any trouble from it, kind of figure it's normal wear and tear showing up. Nice grow you got going.