I see now - the bottom fan leaves.
It doesn't look too bad so far given their age and height. Some of the yellowing looks pretty even, so it may just be from low light because of shading from the upper canopy and the height of your light. You'll also get some normal yellowing due to age towards the end of the grow (especially if you cut down on nitrogen significantly), but it's maybe a week or two too soon for that.
You could try seeing if the Photone smart phone app works for you to see how much light those leaves are actually getting. If it's really low (~50-100 PPFD), I'd just prune them and move on.
If you want to get a head start to see if it's a nutrient issue / etc, you could check with the
infirmary crew. They'll typically ask you for details of your feed/watering schedule, etc. The standard form with what they ask for is here: