Panel 1: When Mike returns, he's shocked by a novel phenomenon: Elly waiting up for him to ask how his evening went.
Panel 2: He doesn't know what's happening or why when she says that she waited up to wish him a Happy New Year.
Panel 3: She then kisses him good night. A warmish seeming moment is shared.
Panel 4: It's immediately subverted by the penny dropping and Mike realizing that Elly was only wanting to see if he'd been drinking.
Summary: Since it probably just now occurred to him what her worry is, it's likely that it didn't occur to him to get gooned so her smile of triumph is wasted and useless like her.