From BTN's Neate Sager:

Make what you will of a report (Josh) Birkholz, 19, who was facing a suspension at Minnesota for violating team rules, "allegedly failed multiple drug tests this summer." That means he is going to the WHL with some questions about character, which the Silvertips would surely have heard about (...) It's not something any firm conclusions can be drawn from. No one is so naive to think 19-year-old elite hockey players are exempt from youthful indiscretions; just look at what happened at Notre Dame recently. The main point of mentioning it is to pass on word of an element of the story that might have been underplayed in WHL circles(.)

Birkholz, 19, was Florida's third round pick in 2009 (acquired in the Bouwmeester trade from CGY). More above, with links.

Update: Clarification from Birkholz regarding the matter.