Always have. Not all the time, but a good 20% of the time. I try to nudge as it comes through.

Just tap the left side when the ball reaches the bumpers. The collision throws the ball off from going SDTM.

Yes, check out this thread:
http://pinside.com/pinball/forum/topic/tech-troubleshooting-tron-gem-sdtm

It's definitely an annoying characteristic of the game. The shot is hard enough as it is. What about mounting some dead drop foam to the ball guide right where the ball exits the Gem area? This would slow down the ball and allow it to enter the pops. The only problem is that it's very tight there, and it would probably affect shots to the right orbit.

I just replaced that post sleeve by the upper right pop bumper by the spinner . The factory one was like a hard plastic so i used a black rubber one that was a little bigger and oh what a difference it made Now when it comes around the lane it bounces right into the pop bumper 2 games no SDTM from the gem shot or the left orbit shot