That sounds unusual. I wonder if your haldex is stuck in 4WD, which in turn is putting extra stress on the flexible coupling? Are all your tyres of same brand and wear etc? If the ecu detects wheels going at different speeds it will engage the Haldex clutch.
My 2012 tdi was 2 1/2 years old with 45k miles when I bought it. It had an intermittent vibration, particularly noticable through the drivers footwell / pedals. This was eventually traced to propshaft damper (Haldex end) and replaced under warranty. The explanation from the garage was the outer steel 'inertia' ring which should be free to rotate was partially seized, presumably by the failing rubber isolator element.