This is literally the 2nd time this has happened to me in the past couple years over two different employers... I go on vacation for a few days and then come back to find that the company has changed my (and my team's) title.
<2 years ago (previous employer): UNIX System Administrator --> UNIX System Engineer
This week (current employer): UNIX System Administrator --> UNIX System Engineer
As always, this doesn't mean more money. So, why do they bother putting forth the resources to do this? All it does for me is force me to order new business cards and change my e-mail signature.