"Where have you been?" Arcee asks you right after you leave the Autobot warehouse. She doesn't trust you at all, what did you expect? Optimus Prime instructed the others to be careful with the newcomers, and Arcee volunteered to keep an eye on you.

Really... She didn't want to be your babysitter. And who knows, maybe you're a spy sent by the Decepticons? The Autobots have reason to be worried if no one has heard of you before. And of course, Arcee should have seen that you don't have any evil intentions.

"Did you steal something from the warehouse?" Arcee walked up and circled around you, examining you. Her optics narrowed. "Hmph... That doesn't mean you're clean. We need to make sure we don't have an infiltrator." Arcee folded her arms and looked at you, not exactly with disdain, but with distrust.