Marco knew that he only had so long before Cassie started thinking he was trying to dodge her. So while he didn't really rush his meal with Kate, he didn't let it go on for two long after the meal itself. He did make sure to post a warning on the way over to Cassie's, so that people didn't come looking for him or get worried. In truth, he found the whole thing sort of funny. He hadn't had to do anything like this in years, and it brought back memories. Plus, he knew there wasn't a Yeerk in his head, so he had no real concern here.
Plus, it was Cassie. He knew this wouldn't be too bad. Now if it were Rachel, or mid-war himself, he'd have been a little more worried. Neither of them were famous for being tolerant when they thought they'd found a Yeerk. Cassie, on the other hand, was the heart of the group. She kept Marco's plans from being absolutely, coldly ruthless and he was pretty sure Cassie was part of the reason Rachel hadn't completely lost her marbles. Cassie and Tobias, the two Animorphs that were closest to their fallen warrior princess.
That sobered his mood somewhat. Nothing like three days tied to a chair followed by telling someone their best friend died in a suicide mission killing your crushes brother and the slug in his head. And then, on top of that, he would also have to tell Cassie about The One assimilating Ax and the fact that ultimately it seemed like she was the only one of them left alive, seeing as how she didn't come with them to space.
So by the time he reached Cassie's apartment, much of the amusement had drained out of him. Outwardly it still looked like he was completely calm and collected, both because hiding behind facades was just his way and because he didn't want to look nervous when showing up to prove to Cassie he wasn't a Yeerk. Strategically unsound was what that was.
He fixed the hem of his Spawn t-shirt and stuck one hand in the pocket of his jeans. The other wrapped against the door of Cassie's apartment. "Potential alien slug reporting for duty, ma'am," he called out jovially, not really caring who heard. Yeerks were really not going to be a huge issue here, what with the lack of Kandrona. Plus, it had been several years since Yeerks had been an issue for him. Not counting the creepy ones that decided to worship The One, but that was an issue he wasn't entirely sure he wanted to deal with yet. Save that for the brief once he got Cassie and Tobias in the same room.