It s been a bumpy PR ride for United Airlines, but this one really stings.A passenger was traveling on board Flight 1418 from Calgary to Houston when he was stung by a scorpion, CBS News correspondent Kris Van Kleave confirmed.The scorpion fell onto Richard Bell s head and stung him underneath his fingernail. We were on the plane about an hour, having dinner, and then something fell on my head, so I grabbed it. I was hanging onto it,  Bell said in a Skype interview.  It was lucky that it hit my nail more than my skin I think, so maybe my thumbnail saved me a little bit. United apologized and offered Bell and his wife a credit for a future flight.As a precaution, crews also checked the airplane for a possible infestation. Our crew immediately consulted with a MedLink physician on the ground who provided guidance throughout the incident and assured our crew that it was not a life-threatening matter. Medical personnel met the aircraft after it arrived in Calgary,  United said in a statement.   CBS NewsSadly, this scary incident took place the same day that a passenger was filmed as he was being dragged off a United flight from Chicago to Louisville by the airport police. United took a huge PR hit after the video was seen by millions. 