I REPLACED MY ATTITUDE INDICTOR THIS WEEK.

[N6784N]

I don't normally think there is a conspiracy against me or anything well other then mother nature!! well and the airplane gremlins!! ok ok and maybe my fiance but thats it... uhmm the government doesn't have something on me do they??  no probably not but anyway I took my plane a few weeks ago to a non mooney mechanic to check out my pc system and I made the comment that my ai wasn't working too well either so he replaced 2 filters that were pretty dirty  that were located under my panel. I didn't get my pc system fixed and replacing the filters didn't help my ai and all that cost me $170.00 dollars. I finally learn my lesson and will only go to a mooney shop which is in fact what I did. They did a great job replacing the ai and I can tell when I look outside and can see the color between the sky and ai match. I was looking at the bill and noticed they changed my filter!!!!! so how many filters are there that can affect the attitude indicator? I'm sure they can tell a new filter from a old one just by the look and if not by my logbook. I have not dealt with this shop before and am concerned since my anual is coming up that i might get charged for stuff I really didn't need to pay for. any answers?