Sam left the Alouettes' training camp for personal reasons last week after being given special permission to return home to Texas.
His departure came three weeks after he became the first openly gay player to sign in the CFL.
The 25-year-old Sam was selected in the seventh round of the 2014 NFL draft by the St. Louis Rams, becoming the first openly gay player chosen by an NFL team. He was later cut by the Rams and from the Dallas Cowboys' practice roster.
A star at Missouri in college, Sam earned SEC Defensive Player of the Year honours in 2013 before turning pro.
The Alouettes play their second pre-season game Thursday at home against Toronto.