Why did Lila steal Dexter's gps?

Hey, I just started watching the show, and I'm currently on Season 2. I have a question that's been on my mind.

Why did Lila steal Dexter's GPS to track where he had been earlier? What would make someone do that? I'm genuinely curious if I'm missing something. Why would anyone steal a GPS just to see where Dexter went, especially considering he works in forensics and his job requires him to visit different, sometimes distant, locations? What made her think, 'Yeah, I need to follow Dexter to these places'?