Ivan and Pao-Lin weren't ones to gossip. Even if they were displeased with Sailor Moon's actions before she was precious to Rei. So Doctor has no idea what Usagi thinks he might think of her. To him she is one of the senshi who worked hard to help them escape and has some sort of close bond with Rei, though just like Rei herself, he doesn't fully understand it yet. That and she is still Serena Lapin from the flower shop to him, and he wouldn't turn a cold shoulder to that nice young lady if he saw her crying.

"Homesickness." He nods his head. Understandable. He pulls a handkerchief from his pocket and offers it to her. "Don't be embarrassed. You've been in Vista city for a long time now. The only reason we're not all homesick is because some of us don't remember just yet," he jokes.