I grew out Nirvana's 'ICE' strain about a year ago.. and came across this with one of them. First time in 3 years of growing that I had ever came across this. I don't think it has anything to do with nutrients..lol. It's more than likely, just the way the plant grew.. had something to do with its genetics man. That's all it is.. just a slight genetic fuck up. Nothing to worry about though bro. Your good! Plant will be just fine.
peace.