KMail Indexes

I was testing Trinity on a system. When I ran KMail I received messages about the indexes. I don't remember the exact message. Something about the index being outdated. On this same test system, after I had uninstalled Trinity and reinstalled KDE 3.5.10, I received similar messages. I again had to let KMail rebuild the indexes. No harm seems to have occurred in either direction. What changed in Trinity to cause this? Any user wanting to use both desktops will have to endure these messages. Thanks. Darrell