For what it's worth, in my case it has been present since the first set of true leaves. Indeed it is likely a freak of some sort, since you would assume it would take a little while for an infection present in/on the seed itself to manifest itself that thoroughly. That's the beauty of so many folks coming together on the internet and sharing this sort of information! Something relatively rare (a random mutation in an inconvenient spot) all of a sudden appears frequent since everyone seeks out a good spot to talk about the freaks and weirdos. I'm pretty risk averse, so I'm wary of mine until proven wrong. There's nothing wrong with being overly cautious!
The weirdo plants are the fun ones. I did a lot of tissue culture work years ago with a few other species, and the freaks were the most fun to watch. Variegation was definitely pretty damn common, and usually came along with other less desirable traits..
The weirdo plants are the fun ones. I did a lot of tissue culture work years ago with a few other species, and the freaks were the most fun to watch. Variegation was definitely pretty damn common, and usually came along with other less desirable traits..


- which is why it's the worst nightmare possible in this industry/hobby, as well as so many others,... So, that said, symptoms showing on the first set of leaves is no assurance that it's not a viral infection, as it is in fact "genetic", expressed, but of a more insidious type! ...... Big picture guys, in the 3 years or so of doing this, I have yet to see a confirmed case of viral infection, and only a few that were looking very likely, due to other co-symptoms and potential sources present of viruses,... In one case, a heavy, messy roll-your-own smoker, handling infected tobacco, then playing with his plants! 
. I gotta say though I don't put much stock in plos one articles with statistical descriptions saying:
Yeah we did an anova, there were main effects and interaction effects but we ain't telling you what they were or if we corrected for multiple comparisons. SCIENCE!