I often thought about the warranty concern for mine too. I bought my 328i in November 2006, so it runs out Nov 2008, and I leave here January 2009, so I will ship my car in December, so I only will be running for about 3 weeks or so with no warranty until I get home, your situation may be different though, depending on when you DEROS.
Call the stealership and check into it though, might be worth it.
2007 BMW E90 328i/6spd. Manual Transmission/Jet Black/Black Leatherette/Burl Walnut Trim/PDC/OEM Front Strut Brace