Not sure what this is/Should I be worried?

Ok, so I'm a newbie grower. This is my first time ever, so I used the PotforPot grow kit with an Amnesia Haze autoflower seed from ILGM. I'm just about a month in from when I planted the germinated seed. Anyway, I just noticed some yellowing on one of the leaves, with a brown splotch on the yellowing as well. The yellowing was on the second leaf to grow after the cotyledon, one of the lower leaves with only three prongs. There was also a little yellow dot on the other second generation leaf. (I've circled both of the yellowing parts in the pictures provided because my phone camera isn't great.) I don't think the problem is underwatering because I'm usually pretty good about making sure that the soil is damp, but I also don't think it's overwatering because even though the plant droops a bit at night (like it's doing in the picture), it usually isn't drooping during the day. The higher leaves look pretty healthy, so I wasn't sure what's happening. If anyone has any advice about what it is and what I can do to help it, that would be much appreciated.

Not sure what that kit includes but you didnt even bury the rooter all the way. You should have soil/medium filling that pot up almost to the top. Usually filled to about 1-2 inches from the top.