The hit took place with just over three minutes left in the second period of Game 3. Thornton was handed a two-minute minor for an illegal check to the head on the play.
Nosek appeared to be shaken up after the hit but stayed in the game.
Thornton has been suspended just once over his 21-year NHL career. He was handed a two-game ban in 2010 for a controversial hit to the head of St.Louis Blues forward David Perron.
The 39-year-old Thornton recorded his third point of the series on Kevin Labanc's first-period tally in Game 3.
San Jose faces a 2-1 series deficit entering Game 4 at T-Mobile Arena in Vegas on Tuesday.