What would cause my MSL to change?

[ou2mame]

thats weird because i thought i wrote my msl down wrong because it wasn't working last week. i checked it again, and it was a completely different number. i know it was because it started with 612, which is the minnesota area code, and now it starts with 113. odd right? i hadn't used it in a month or so, but i did a hard reset and restored with a sprite backup and wanted to check a few things cause picmail wasn't working. i have no idea how/why it changed. it has never changed after a hard reset previously.