To me the wording is clear and means they have heard arguments before. But the person who sent the first message won’t accept that the response they received implies that. AIBU?
Message someone sent to their neighbour:
“Dear Kelly,
We apologise for any disturbance last night. Jack and I had some disagreements, but we made up now.
Elaine”
The response from the neighbour:
“Hello Elaine, I’m always concerned when I hear you and Jack. Everyone has a disagreement now and then but I’m glad everything is ok now. Take care.
Kelly”
edit: my favourite part is that when I explained the response to the original sender, they refused to accept that it meant more than one occasion, and then shouted at me over it. I’m doing this to show them they’re wrong as they don’t believe me.