Ph issue in rockwool or what am I looking at?

[TrichomeChaser]

These girls been in veg two months, no problems at all. Just got into 5 gallon air pots with mini rockwool cubes. I use gh line for nutes. Noticing this weird deficiency or issue. Very sporadic on where it is. You'll see it affected a whole branch basically and is barely visible anywhere else. Is this a pH issue a deficiency? I have not seen any bugs at all but the holes are what throws me off
I am ready to put them in flower but I would like to figure this out first. Thanks for any and all help

 

[TrichomeChaser]

Veiw of the whole plants

 

[mjinc]

Have you been checking the ph of what you are feeding your plants and what the runoff is? Looks like a ph problem to me but testing would tell you that

 

[TrichomeChaser]

Have you been checking the ph of what you are feeding your plants and what the runoff is? Looks like a ph problem to me but testing would tell you that

Just checked it on yesterday's watering. Ph going in was 5.7 and run off was 6.2-6.4 on multiple plants

 

[mjinc]

Just checked it on yesterday's watering. Ph going in was 5.7 and run off was 6.2-6.4 on multiple plants

That seems about right. I would continue with the calmag in low doses for the time being.