Start on the right foot

I met the neighbor tonight. The landlord had told me her name, we'll call her Jane Doe. I said "hi, are you Jane", she responded very politely with "yes, I'm Mrs Doe". I'm worried I offended her by not using her last name :( Sounds like I'll have a bit of relationship building to do and I'm a little embarrassed that it didn't even cross my mind to use a more polite introduction.