Well it does look a little small. How far away is your light from the top? Is it adjustable? Many problems start with incorrect ph, and overwatering. Did you soak down your soil before you put it in there, or just plop it into a bucket full of dirt? Last item, you put a seedling into a 5 gallon bucket so the roots are having a while to move down, that will keep a seedling short for a bit. My best guess is overwatering, and seedling in 5 gallon bucket. It doesn't look stressed, just small so dial back the watering. A lot of people baby the seedlings under low watt cfls, (think 65w or 85w) until they get a bit bigger, then after 1.5 or 2 weeks drop them into the grow medium to veg. There are other schools of thought that say just plant autos right into the grow medium and have at it. I personally prefer the first method. Whatever you do, do not give that thing any nutrients for awhile, it's still in seedling stage. Check your light manual for distance for seedlings and make sure you are at that height and adjust accordingly. Hope that helps. Btw, I did the same grow as you, same seeds, WW-Auto from ILGM. It's a great hobby! You are gonna love the flavor! Good luck!