Fuel injectors three and seven are misfiring

Last week I took my SUV to the dealership for its 100,000 recommended service. Prior to this service I had no problems with my truck. The service included oil change, tune up, fuel flush treatment, transmission flush and radiator flush, and tire rotation. One week later I was driving down the street, and my engine started shaking the car. As well as the car sputtering. So I immediately pull my car back to the dealership where I just received my 100,000 service. They call me, as said my" fuel injectors three and seven are misfiring. This was bounded to happen and it would cost $1,000.00 to fix." so my question is, would a bad tune up cause my fuel injectors three and seven to misfire? Or is this a problem I have to suck it up and bite the cost? Thanks for your time and assistance with this matter.