1st grow, looking for a leaf diagnosis. Please help

[gumby29]

This is my first grow ever (still learning) but my plants and 24 days in growth. I recently noticed one leaf has a brown tip. I don’t see any others on either plant and it is not the closest to the lights. So I’m thinking it is not light burn, I was thinking maybe ph issue? I just started with nutrients just after I saw this.
I’m growing in coco loco, 18/6 lights. Using Dyna-Gro superthrive grow ( but half of what is recommended) and my ph has been around 6.5. Any thoughts?

 

[Captspaulding]

Just looks like that leaf had been resting in the dirt at some point froM my front porch.

 

[Jeffdaman]

I agree they all look very good man good job

 

[gumby29]

Thanks for the help. I’ll keep at it then!!!