NEW: Does Chris Matthews want his executive producer fired because of his mistake? 

Original report, June 19, 7:35 p.m.:

“We’re all reacting here… putting on shit,” Chris Matthews just yelled after coming back from a commercial break before realizing that he’d gone live on the air. The verbal slip-up occurred during the second live airing of his MSNBC “Hardball” program today, and it’s believed the “shit” he referenced was a pre-packaged interview with the now-independent NYC Mayor Michael Bloomberg by NBC lead anchor Brian Williams.

“I apologize for that,” Matthews said in a solemn voice after the Williams report aired. ”I shouldn’t have used that word on the air.”

The gaffe comes on the same day that Matthews was booed during his questioning of Hillary Clinton at a labor forum in DC. It also comes only weeks after some have begun speculating whether the diabetic talker is drinking too heavily in his private life.

Earlier: Chris Matthews’ Secret Death Scare; Chris Matthews: Drunk As a Skunk?