Yellowing to slight grey leaves

Yup I think your spot on looks like a ph issue to me but i can see why you would think it was a defiancy she is rather pale in places. This I would put down to lack of nitrogen. But that would only be second guess to ph problems autos are notorious for not needing much at the start and then exploding in growth in the first few weeks of flower so I wouldnt pump her full of nutes just incase. Id give her half dose of feed when she has dried out and see how you go but this week I'd give her a flush for a week when dry and then re evaluate the situation they dont need much at this stage :)