Search pulling up entries missing search items

I did a board search for *Tiesto * and I got two recent threads that had no Tiesto located anywhere.
http://boards.straightdope.com/sdmb/showthread.php?t=358282&highlight=Tiesto

and

http://boards.straightdope.com/sdmb/showthread.php?t=366293&highlight=Tiesto

It’s not a big deal as I found plenty of other threads, but I’m curious as to why that might happen. Was there once a post with the text *Tiesto * in it, but it was deleted for some reason?

Both threads do have the word Tiësto however (and both times it’s Yookeroo who posted it).

It looks like the searching engine is able to match up “Tiesto” with “Tiësto” (note the umlaut(?) over the E) but the highlight engine isn’t.

It looks that way. I guess I’m spoiled by the red highlighting.