I usually call that having a 6th sense or using one of the other 5 , you can smell it coming. I'm sure many of you have done this from time to time. So I'm not saying I'm the best rider, but I have saved my own bacon many times just from eyeing someone approaching just as Bob did. You might say to yourself, watch this idiot do something stupid and sure enough.....there it was.
Good call Bob and glad you made the right move. TM