Sif knew Thor was perfectly capable of taking care of himself. He was one of the strongest of their pantheon, perhaps even stronger than Odin. There was very little reason for concern, but he was her husband and she was entitled to worry from time to time. Especially when he was running around with Loki's children. That in itself unnerved her. They were all not to be trusted and she felt Thor was letting them get the better of him, even if he was fighting back. Had she been a fighter she would have gone after Fenrir.
When she heard heavy footsteps she knew he had come home. And then came the noise of fridge rummaging which only made her chuckle and smirk. Of course that would be the first place he went to when he came home.
Had Sif's hair begun to turn black because of those horrid Thor comics she would have rained down a storm of hurt on those idiots. Luckily most seemed to remember that there was a difference between comics and myth. She was thankful for the ones who remembered. It saved them all a great deal of pain.
Even if there were no plans of going out, she was going to basically force him to stay in that night and spend time with her instead of gallivanting around the city looking for his hammer. (She did want him to find it, she just wanted him to herself for an evening.) So she dolled herself up so he could get the hint. If her flirting before hadn't been enough.