I think your ok here. Mine does that every now and then during game play and places a perfect shot up the left barn ramp and around on its own. I posted on it but no one had an answer. I long ago decided it must get triggered and have something to do with what happens during play and the rules that we don't yet understand. Think about it - if it does that and the music doesn't change to the slow crossbow music then it's not giving you control of the crossbow so hitting the fire button isn't going to do anything here.
Interestingly, this happened to me once where it loaded the crossbow on its own, music didn't change to the slow crossbow music so I wasn't in control, and it fired a perfect shot right up the bicycle girl ramp. I freaked out. It was the first time a bicycle girl ramp shot was achieved on my machine via the crossbow.
(Since then that's the only shot I like taking when I'm given control in the crossbow mode because it is so satisfying to make)
Since it is not going into ball search mode and it is hitting targets perfectly and not actually going into crossbow mode where it gives you the control, I still say it is something in the code we haven't figured out yet.
When it happens to me there is just too much going on so I have never been able to figure out what occurred during play to trigger this. But I like it. Shows you how deep our Rules are really going to be when the code is finished someday.