i dont know a whole lot, but check your ph. ^^ they are right about it looking like the beginning of nute burn, but i wouldn't just let it go, i would check to see where your at with the ph level. Even if you dont have a shitload of cash to spend on a ph meter, just go out and get yourself those ph,alkaline,and chlorine level tester strips for swimming pools. At least with that itll give you a decent idea of where your ph and alkalinity is, and you can correct it. I let my plants go when they just had a couple yellow tips, and within two weeks, i had fan leaves gettin yellow and brown, crispin up, shriveling, and bottom leaves falling off. My plants had locked out all nutrients cuz the alkalinity was way too high in my soil. its an easy fix though, so check before you look at it one day and your like "WHAT THE FUCK HAPPENED?!", lol. theres a big article i posted just a little while ago about checking ph levels and other plant/leaf problems and indicators and how to fix them. got it from 420 mag online, and it saved my royal ass in a serious way. Check it out man..