Time Machine? Okay, what? Now she was relatively sure this guy was nuts. Sure, she believed in time travel, that wasn't an issue. Believing there was a machine that did it? Okay, that was a little more weird. And it traveled in space, too? Seriously weird.
But then, most people wouldn't believe a word she said if she told them the truth about her. A few times, she had, and people hadn't. Jason, for instance. Stupid men. But she should've expected that, really. And in fairness, he did sort of make sense, even if he had a slightly overdramatic way of explaining it. One minute she was comfy cozy (sort of) in Halliwell Manor and now she was...well, here. Wherever 'here' was. Other than Mickey's Diner.
So she followed him. Probably wasn't wanted but she was too curious to care. This guy didn't make much sense, but in some ways, he did, and she wanted to grasp why. "Who are you? How do you know all of that? A space machine? Isn't it a space ship?" That's right, Phoebe, pick your battles carefully. Space ship versus space machine was definitely an important one.