Yeah, after looking at my book (which has been a life saver for me personally -- Marijuana Garden Saver: a guidebook for Healthy Plants by J.C Stitch), Im pretty convinced that this is nutrient burn. The way that the leaf has shriveled n crisped up, without yellowing hardly at all is a telltale sign. So i would again ask that you include some pics of the whole plant, along with the doseage of nutrients your giving it. Please try and include the rest of the information aswell, and im sure that somebody will be able to give you some great help, if im not able to come back n help out later.
Also, check out RIU's FAQ section. Read the entire thing, its a pretty comprehensive guide on how to grow cannabis. If there's a problem with your plant, the FAQ addresses it. It also has a bunch of great information on how to improve your plant during its life cycle in your garden. Even while using CFL's, you can still pull a great yield from your plant if you treat it right. Have you visited the forums' CFL growers section? it's full of people who grow with nothing but Compact Flourescents, and they all pull some absolutely amazing things off with those little bulbs man. In ALOT of cases, their yields rival even an HID growers yield. It's worth checkin out.
Hope i helped

n if you can, PICK THAT BOOK UP!!!--well worth the 14 bucks, lol.
-K1.