I agree its hard to see in the out of focus photo.
Calmag issues would lead to spots, but it looks about a week old so I wouldn't think it would be showing any sort of deficiencies so early? I grow DWC and I don't use nutes for the first week or more, just ph'd tap water and they grow fast and healthy. Its hard to bugger up that fast unless you go with too much nutes too soon or are all out of whack ph wise.
But hard to say without more info and a decent picture