I'm not sure that I agree with the StringBuilder comment. I assume you were thinking it would be more efficient, and it would be, but I also remember some thread where people were looking at the efficiency achieved. Basically, if you are only doing a handfull of concatenations, which is likely in this case, then it's kind of a wash.

So don't be too hard on yourself about it. StringBuilder probably would be an improvement, but it would only be a noticeable improvement if the search had an abundance of terms. That's fairly unlikely.