Don't think it was a PED, Sonnen and Overeem both got a year, Feijao got a year, everyone who gets popped for PED's or over doing their TRT always gets a year.
It was probably pot, he was moving up in weight so I'd be surprised if it was something to help the weight come off.
2013 VIP FFL Champion
THE RETURN - 9/27/14
Machida - Alves - Cruz - JDS - Weidman - Pettis - Edgar - Cowboy - Dodson - Okami