Hi all, this is my first grow. I have 10 Big Bud plants (100% germination from Nirvana) all set up in a hydro system right now, and I'm looking forward to see who my mother(s) will be

However, I have a slight problem. I'm a huge noob, and can't tell whether or not a nitrogen problem is coming up. The tips of the center fingers on a few leaves are just starting to turn yellow. I don't have pictures up right now, but I hope to have them up soon. Any suggestions? Nothing other than the tips (about 3 millimeters in) are yellow. I might just be freaking out, but I'd rather flip over a problem that isn't there than miss a problem that IS there. Any input would be much appreciated!!!