hi
I have been there many times befor, I don't know if it was the way I steer my car or perhaps the way I hold the wheel when I drive, but it have happened to me 3 times now!!!!!!

and the gulty part is the Steering Column Bushing-Bearing, it is a cheap part but vary labour consuming; you have to remove the steering column and replace this Bush-Bearing

some how this bearing or bushing just comes lose of it place from underneath the column and the wiggle starts, and as you said one day the car was fine, the next day there was the wiggle and it was very scary to me the first time i faced this problem, i thought the wheel would come of while i am driving