Did you know that 420 magazine holds contests on a monthly basis? There are some very generous prizes given out by the sponsors on this site for these contest winners too. The three categories are:
Nug of The Month, Plant of The Month, and most importantly to me is
Member of The Month
Any 420...
The following article link is informative with great pictures.
One note: in the article is states that the only way to tell the sex of the plant is force flower or to put clones into flowering light schedule. This is not true, you can sometimes tell sex of plants during the vegetative stage...
Consensus opinion is that this is probably light nutrient splashing on the leaves, or they could have been slightly damaged during a move or placing into the scrog screen. There are little spots on the top leaves and some in the bottom corner of the picture.