Armstrong sent a tweet on Thursday saying "Just got kicked off a Southwest flight because my pants sagged too low...no joke!"
Armstrong was trying to fly from Oakland to Burbank. Cindy Qiu, an associate producer for ABC7's "7 Live" was on-board the flight and witnessed the incident involving Armstrong.
"A flight attendant approaches him and says, 'pull your pants up,'" Qiu said by phone on Friday. "He says, 'don't you have better thing to do than worry about that?' and then the flight attendant says again, 'pull your pants up or you're getting off the plane.'"
Southwest Airlines spokesman Brad Hawkins released a statement Saturday morning.
"We reached out to apologize," the statement read. "We followed up...and understand from the customer the situation was resolved to his satisfaction."
Southwest Airlines says Armstrong was allowed onto the next flight from Burbank and said he had no further complaints.