Yes, it appears to be fairly common in the '07s. The plastic walls of this double-row ball bearing seem to be the weak link, but the replacement looks the same and future models use the same part. Maybe, hopefully, they improved it. I don't agree with your dealer about the heavy gear oil causing the problem. Ask him to provide evidence for his claim, as without it you can't link the two. I've used 85w140 and heavier (Redline SPH) since new and still do. If I thought it was a problem I wouldn't use it.
Mine started whining at about 16k but nobody could link it to the tranny at the time, and I blamed everything else (tire, belt, etc.)--but by 32k the noise increased and it started groaning. I reported the whine before the warranty expired and HD agreed to repair it in warranty even though it had expired 10 months before. Big job and I'm glad I didn't have to pay for it. If you must do this job consider the SE compensator upgrade, which should go in with no additional labor charge.