@GrumpyWolf i believe it depends on the type of test being used (antigen, PCR) and the length of time between exposure and testing.
Rapid results tests (antigen) depend on a threshold amount of antibodies in the sample collected to be considered positive. It's possible that your partner was on the cusp of hitting the threshold between the two tests.
https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html
@GrumpyWolf @doingitright
@f_gundersen It's possible, but either way, I can't really go anywhere for the time being just to be on the safe, even for me.
I'm crazy, but not stupid. I'm not going to put others at risk if there is a chance to cause others issues.