I keep finding strange things in my apartment that don't belong to me, should I be worried?

I live alone. I haven't had anyone over in quite a while. And no one that would've been over uses the stuff I found, and it couldn't be any of their's.

Yesterday, after I got off work, I opened my cabinet and right there in front of my bowls was some body jewelry. Like what I wear in my cartilage piercings, except it wasn't mine and I'd never seen it before. Also, I don't know anyone else with piercings to accommodate this type of jewelry. Yesterday morning when I had breakfast before going to work, they weren't sitting in front of my bowls. To my knowledge no one has been in my apartment. But SOMEONE had to put them there, and it wasn't me.

I also found a mysterious tube of mascara in my apartment. Not my mascara. Everyone I know says they've never seen it before.

I know I sound like a crazy person... but this kinda gives me the creeps... Should I be freaked out that someone seems to be putting random stuff in my apartment or not worry about it?
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+1 y
There's a master key. The manager and the cleaning lady are the only two people with master keys. I don't think either of them just hand the key to the maintenance crew so they can let themselves in to people's apartment. I always see either the manager or the cleaning lady unlock the door for them when they're going in to other people's apartments. I don't think that anyone but them have access to a key to my apartment. So I don't know if changing my locks would help, since there is a master key.
I keep finding strange things in my apartment that don't belong to me, should I be worried?
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