Sawyer looks for Sayid, Horace finds Kate with Sawyer, Roger's keys in cell door

Sawyer is at the security building checking the various cameras for Sayid. While he's looking, Kate comes down to ask him about Ben and Sayid. Sawyer tells her she needs to stay quiet and stay out of it so she doesn't cause more trouble. Horace, Phil, Miles and Jin come in and Horace asks what Kate is doing there. Sawyer lies and says he was asking her if she saw anything suspicious and tells her that she can go. Horace asks Sawyer if he's checked out the cell yet and he hasn't saying that he as been busy trying to keep the town from burning down.

When they get to the cell, a set of keys are hanging in the lock. Horace points out that someone let Sayid out and Sawyer points out that they're janitor's keys. Horace says the only janitors (workmen) are Roger Linus, Willy and Jack. We learn later that they're Roger's keys. Sawyer volunteers to take Miles and talk to Jack. Phil once again looks very suspicious of everything.

Why would the janitors have keys to the cell? Wouldn't it be left open when no one's in there and why would it be important for them to clean it when a prisoner is being held? It's all pretty odd.