The 24-year-old and team-mate Marlon King were sent home from World Cup duty with the Reggae Boyz for leaving the team hotel, but Humph has blamed a communication error as the reason for his early departure.
He said: "There has been a communication problem. After the game in Panama I did go out. It was late after the game and to unwind I went out for an hour.
"I had not been informed of any curfew and no-one told me we were not allowed to go out. I fully accept the fact that I did go out and on that basis I have apologised to the team and accept responsibility."
Morton have completed their fifth summer signing with the capture of 20-year -old former Motherwell starlet Jordan Halsman.
Kilmarnock have announced that they will play Sheffield Wednesday in a testimonial for Rugby Park servant James Fowler on August 8.