I don't think that is a stress fracture of the paint. First off, if it was stress related, the paint would appear to crack. That looks like it's been scratched with something, especially looking at the bottom of the 2nd pic where there appears to be a loop made at the end of the scratch. I don't think you will ever see that with stress cracking??? Do you park the bike outside for any length of time? That looks like someone "keyed" your tank with a sharp object. Anybody you know jealous of your new purchase? That would really p_ss me off....
Oh, and welcome to the forum.