Estar and Ser regarding marital status

Hola Ron

To be honest, I can't see that association as a native Spanish speaker. In Peninsular Spanish we always say "estoy casada"; when we may use soy casada is in very formal situations, for example if you go to an interview and you need to say whether you are married or single, you may say "soy casada", but it would be unusual in any other context. 

This may differ a bit in Latin America, though, where my feeling is in some Latin American countries, the use of ser may be more common. 

Saludos

Inma