The best thing you can do Is leave your seedling the hell alone. Let it progress a little then you can start looking for problems. Most new growers make the mistake of over loving their babies and screwing things up.
Some plants take on a purplish hue naturally or when subjected to lower temps... I'm in agreement with a lot of the other posters... Don't look for things to worry about, they'll find you in due time! Best of luck!
We all been there, treating em like newborns, sleepless nights, routine inspections and a whole world of paranoia lol
Let em do what they do best and trust them to tell you when things are not going good.
Goodluck