Early on in the movie, Lori goes to bed early, so Quaid heads to the bar to catch a few drinks. Harry then asks him, "Lori working tonight?" and Quaid nods, "Yep", sparing him the details that she is actually just asleep. Harry operates on the belief that Lori was at work when he later tries to talk Quaid down. Since undercover Lori is an operative, Harry doesn't know what her cover story is, so just assumes that the claim she was at work was part of Lori's cover. If he really had gone to collect Lori in the real world and Harry really was at Rekall, Harry would have known she was at home because that's where he would have found her.
