creating security token updates all user in membership table?

Hi All,
I am trying to create a security token and when I run:
token = SPSecurityContext.SecurityTokenForFormsAuthentication(base.AppliesTo, authProvider.MembershipProvider, authProvider.RoleProvider, username, password); It updates every user entry I have in the aspnetdb membership table by changing the LastLoginDate to the current time for each record, not just the user that is passed as username in the above parameter.  Does anyone know how to keep this to updating each record.  I know it is that line of code for sure.  I just dont understand what is it running in order to update each users record. 
Here is more code that surround this but that line above is in GetSecurityToken().  I would really apprechiate any suggestions
Thank you,
Nici
protected void signInControl_LoggingIn(object sender, LoginCancelEventArgs e) { Secu ...