Both indicated that their underwriters would likely check up after closing - 30 or 60 days after - to check on income at that point, to see if there were problems, and that this was somewhat normal for them with self-employed folks, but wasn't anything related to c19 (which... I suspect some changes may occur to underwriting and loan processes in the aftermath of c19). They indicated this was just something that happens to 'a moderate portion of self-employed borrowers post-closing'.
I'm not sure what they could actually do to you if they found your income had gone down or away post-closing. I was going to ask in our next call, but ... we're probably putting that whole project on the shelf for now.