I am not surprised by this.
My wife was diagnosed Covid-19 about 2.5 Months ago. She had a fairly mild case (Shortness of breath, dry cough, body aches, loss of smell or taste, exhaustion, ect. but no Fever). Anyways I sat next to her on the couch for the next 2 weeks and the week before she was diagnosed. I slept in the same bed as her. We did not sanitize the house even after her diagnosis. I might have washed my hands "a little" more frequently but not significantly more. Anyways I showed minor symptoms, tiredness, dry cough, shallow breathing (I was able to take deep breaths if I consciously thought about it).
Note I do live in a hotspot in South Florida.
I got an antibody test done 2 weeks ago and it came back negative. So either. My wife had a false positive (unlikely due to symptoms), I had a false negative antibody test, Covid is not as contagious as thought (if treated early), or my body didn't create antibodies as discussed in this article.