I tend to agree with
Fahrenheit531 . It's unlikely things are going to catastrophically and dramatically fail. And likely that whatever is wrong isn't going to cost significantly more to fix when it does finally let you know what it is.
Do be aware and investigate possibilities when ever your think of a possible cause, but don't drive yourself nuts looking for it.
And if your bike shop mechanic didn't tell you it was just a guess about the noise when they dealt with it, then shame on them. Though I suppose coincidentally it might be that the other stuff was still needed at the time.