Can it be bad (health-wise, besides exposing others at the appt) to get the vaccine while having covid? like if you got a false negative test or unknowingly have it asymptomatic? (no hesitancy about the vaccine, dont need encouragement just curious?

It is hard to be sure about most issues related to this new disease, but some things are apparent. Maderna Vaccine is not recommended within 90 days of SYMPTOMATIC covid infection. It appears those who never have symptoms are not considered at increased risk and do not spread the virus as much as once thought. Numbers are down nationwide, in Texas below 4% testing positive for 10 days.

I am impressed by your concern for others at the vaccine administration site. Screening prior to the vaccine includes a question of whether you have had COVID, and the followup is to defer vaccine until 90 days out. That was however, meant to allow unvaccinated and unexposed people to at least receive a shot. There is no known problem with receiving the vaccine sooner.