Just spoke to Sovereign Bank Lost and Stolen Card department. It is a SCAM. Do not reply. They have received many calls about this since 8am EST on 5/27/12
My wife,Sons and I too were texted from the 406 area code number. Since neither of us have an account with Sovereign Bank none of us responded to the text. However, the more I thought about this the more I was convinced that it was a scam. Hopefully they will find the people responsible.