its hard to say - but does look like temps might be getting a little high - what is the PH of the water you use?
To me, it looks like it may be getting a little too much nutes even though you say you aren't feeding, that soil likely is a bit hot. It doesn't look terrible, just correct your environmentals and if you want 'perfect' looking grows, I would just stop using 'pre-fertilized' soils as it makes things harder to control, I don't think this issue is going to greatly impact your grow here