whats up with this branch???

iv noticed for a few days now that the branch in the middle of my plant is very droopy and a lil bit curved and almost looks like its a bit dead, but what i cant work out is that this is the only branch on the hole plant that is doing this, im using a 65w CFL blue spec grow light and a full spec 15w florescent light, im useing MG all purpose compost that feeds up to 3 months mixed with perlite, i water when nice and dry (every 5-6 days) and i have a small fan for air circulation.

hi does it not just need a cane to keep it up :cool:

like i said the plant is fine apart for this one branch, which all the leafs are droopy and it dosent look healthy its not falling over

i really need to no as im worryed for her amn, someone must noe????!!!!