It's more often ph being off. Plants that small are never really deficient unless the soil is horrible. It hasn't lived close to long enough to exhaust that soil of anything yet. Lack of air to the roots can also cause droopy or bad leaf posture. Some deficiencies will cause twisted leaves but again, too young for that. You can grow for 10-20 years and never see a boron deficiency. That's probably one of the most rare next to copper deficiency. You just never see those micro nutrient deficiencies hardly ever because the amount of boron a plant needs is so small it most likely has more then enough even if your soil just has trace amounts. The most common deficiencies are nitrogen, phosphorus, potassium, calcium, magnesium and iron. Those are the six elements a plant consumes the most of. I've never had a deficiency outside of those 6 elements. A plant only needs 1/10th of 1% of it's feed to be iron. After iron the amounts of elements the plant needs are so small it's rare to be deficient in them. Sulfer is also quite important but again it's needed in such small amounts and it's such a common element that's part of many of the magnesium compounds and others that the plant almost always has too much.
That's right in range for ph. Many rookie growers get a little ocd on the plants when they're small or have the slightest thing off to them. Just keep it moist and keep the light on, it will keep growing most likely. It looks pretty healthy to me. If it continues to worsen we can make a plan of action. I did notice there seems to be a lack of perlite in your mix. It's a good idea to run about 20% perlite or so to aid in drainage and aeration. This also help the soil resist compaction. I prefer course perlite. I find the standard stuff too small of a particle and the larger courser stuff is more effective. I use precision perlite course. You'll find it at any good hydro supply store it's only about 15-$20 or so for a very large bag.
i was looking for perlite but im in Brazil in a small town....imma check other stores...i can get worms too right? heard it helps
Tbone knows his shit Said everything I would have said.. so instead, I'll post this.. Good luck with your grow. It's looking good so far, don't worry so much