Job Interview Mishap

I recently was looking for work and landed a few promising interviews at some prestigious places. One place was a university and I arrived there early with time to look around and observe the people at their work. I met with the interviewer and we talked for a good 45 minutes to an hour. I was answering his questions just as he was firing them, it went great! We were on the 2nd floor of the building at the time and so when it was time to go, the interviewer and I started to descend a staircase which led to a lobby area. Well, just as I was saying, "Yes sir, Mr. Smith, you can rest assured that I am one of the most careful people that you can find ..." Just at that moment, my foot touched nothing but air and I could feel myself descending rapidly halfway down the staircase. My knee was scratched but I was ok. I could tell the interviewer was probably biting his lip to keep from laughing see me roll down the steps like a barrel. The first thing I thought of was that I wanted to make a hasty exit like Curly from the Stooges would've when he gets embarrassed but instead I mumbled, "I'm ok" and thanked the interviewer for his time and ran out. Thankfully, no one was in the lobby otherwise I probably would have made an even bigger scene than what happened. Needless to say, I didn't get a return call back or even a rejection letter. Oh, and the job I was applying for... well, it was handling sensitive and expensive equipment, IT kinda stuff. LOL!