Good grief folks. A disciplinary issue isn't the end of the world and this early on it can certainly be corrected.
He could be having issues in his personal life w/family, friends, or a girlfriend which are causing him to have an issue with his attitude and not giving his all. When things get toxic off the field a person can become someone who just drains the energy out of everyone else because they're down and angry. That's why coaches worry about attitude -- it has little to do with smarting off and more to do with whether a player has started to spread his mood to others.
Or for all we know, Lane went on Spring Break and had too good of a time like every other college kid and so failed a test. (I'm speculating here so please don't take that as gospel). A lot of guys don't realize how long that junk can stay in your system and depending on your body weight and metabolism mj can be detected for weeks after use.
Or for all we know, it was just lot of little things that added up and it was more a decision to let Lane cool off and figure stuff out so he could come back better than ever.
At any rate, it's not the end of the world and right now is the time to deal with issues whether they're big or small. Hopefully it's something small and it's set to right soon.