[TahoeM3]

I've had a check engine light pop up this week so I took my X5 in for service. I've had some roughh idle and o have noticed more black soot on the exhaust surrounds. They are telling me that they found the injectors are the problem and are replacing them. Has anyone else had this? Seems kind of odd to me. I have only had this X5 since last March, although it does have 20k miles on it.