“Do I expect this to start a relationship, ch”v? No, I don’t.”
exactly!
what you are doing is adding a geder on top of a geder on top of a geder. Which is not wrong, but it is important to understand.
chazal knew what they were doing they assered yichud, they cautioned “aL TARBEH sicha im isha” They did not say DONT return lost items. The gemara brings the story of Bruriah who was asked “ezeh derech L’Lod” she scolded for not asking more directly “eizeh L’Lod (apologies if I missed a detail but that is the gist) a MINIMAL amount of interaction with members of other gender (directions, returning key, informing regarding lights) is wholly approriate. Arguably treating such benign exchanges as taboos that have know been violated is more dangerous than simply saying “Hi you left your lights on,”