A Washington state senator was arrested at a Hong Kong airport last week for having a pistol in his carry-on luggage, his office said Monday. Republican Jeff Wilson was charged with possession of an unregistered firearm and was released Sunday after posting bail ahead of a hearing on Thursday. In a statement, Wilson’s office said he was on a flight from San Francisco to Hong Kong to begin a five-week vacation in Southeast Asia when he “reached into his briefcase for a piece of gum, and felt his unloaded revolver inside.” He had not realized the gun was in his luggage when he went through security in Portland, the statement added, and the baggage screeners also “failed to note it.” Wilson immediately contacted customs officials about the weapon when he landed on Friday night, his office said. “It was an honest mistake, and I expect the situation to be resolved shortly,” Wilson said.