It seems like a fairly common occurrence for me. Many times higher than 5%, it seems to happen in over 20-30% of my games. I play lots of minor games at extreme speeds (on a fast computer) and it's remarkably annoying, it was very rare(5% makes sense) up until either 1.03rc1 or 2.
I believe there's a setting you can change to make sure people take the historical choice each time if that's what you'd like.