They asked me about this at the NVC level. I had sent them 4 of the 5 documents they said they accepted for proof of domicile. I think they didn't even bother to look. I sent them the 5th type of document with a note saying they got 4 from before, anyone of which work and now they have all 5. I think they are VERY busy and confuse cases as they go through them. I have owned my house for 20 years as well.
I got 19 approval notices for my I-130 before I had submitted all the docs they requested at that level. I think there was a glitch in the matrix at that level. It an overwhelmed system.
Don't worry, you can always count on them to....?