Shemar Moore: Hey Thomas Gibson, Karma's a Bitch

Shemar Moore didn't mention Thomas Gibson by name, but he's almost certainly taking glee in his former co-star getting the ax ... saying it's all about karma.

Shemar and Gibson had beef during their stints on "Criminal Minds" ... loud arguments on set to the point Gibson's ex-manager had to talk Gibson out of physically going after Moore.

TMZ broke the story, Gibson kicked a writer in the shins during an argument on set. He was first suspended and then fired by CBS and ABC.

Moore deleted the video after posting it, but we all know how that works.