ABC News' Sunlen Miller Reports: Barack Obama's presidential campaign plane made an unscheduled landing in St. Louis, Missouri, due to a maintenance problem.While flying from Chicago to Charlotte, the pilot's first officer announced that they were experiencing "controllability issues" with the "pitch" of the MD-80, describing it as a "minor little problem" but significant enough to force the unscheduled stop.Upon take off from Chicago in bad weather, the plane made an abnormally large dip and flight attendants hurriedly placed items in overhead compartments."We're doing O.K.!," Obama, D-Ill., said to the press after the incident, "A lot of excitement, huh? So everything is fine guys. Just thought we'd spice things up a little bit today. Don't you think?"When asked if he was worried at the time, Obama told his traveling press corps, "Anytime a pilot says that something's not working the way it's supposed to, then you know, you make sure you tighten you seat belt. Everything seemed under control, the pilots knew what they were doing."CLICK HERE TO WATCH VIDEO OF OBAMA AFTER THE PLANE'S UNSCHEDULED LANDINGThe presumptive Democratic nominee was aboard the plane at the time of the incident along with 44 additional passengers, including nine campaign staffers, a number of journalists and a protective Secret Service detail.The landing in St. Louis was relatively smooth and the campaign initially considered moving Obama to a private airplane terminal but changed plans upon protests from the press. The candidate was eventually moved to a nearby hotel with a small number of journalists traveling with him.The campaign has since announced that they will cancel Obama's scheduled event in Charlotte.While still aboard the plane on the St. Louis tarmac, Obama milled about the front of his cabin -- reading his blackberry and he spoke to the pilot briefly. Staff opened large trip binders and talked to him (as they do on the plane ride) presumably going over details of a trip or a speech. The candidate is calm, at one point turning around, put his hands up in a mocking type of fear, clearly downplaying the situation and poking fun at the press filming his every move.Press are busy filing, phoning in stories and sending back video; according to the Obama campaign, mechanics are still "checking out the plane", which is not Obama's regular campaign plane. The private campaign plane he usually flies is in the process of undergoing renovations for the general election.