I had not seen a classic stern “tilt-through” until this weekend at the upstate NY championships. It is an interesting case to be aware of. My 2nd hand understanding.
Stargazer. P1 hits spinner. Hard slap save attempt as it drains. Spinner still spinning and starts accomulating point for P2, qualifying the playfield. Tilt before plunge.
“Play as Player 1/3 Only” FTW 
Yup. Had it happen to me before in a casual game on my Meteor. Juicy spinners on a fast (aka fast-draining) classic Stern will do that to you. And from the bit of the Upstate NY stream I watched, @drgnlair 's spinners are most definitely juicy. Loved it!
It’s good to remind people that it is possible (albeit much less likely) to tilt through on a classic Stern.
I’ve seen this on bally spinners too… (no surprise… same stuff). I actually had a problem where the switch trigger point allowed the spinner to trigger from the wobble as the spinner would settle and cause a similar problem. Needed to clean up the switch adjustment so more rotation was needed before the switch would trigger.
a bit annoying when the games are on coin drop 
I try to dial mine so that they rip nice and long, but take almost a full revolution before the switch registers.