$50 Counterfeit Bill. Any Reason To Actually Be Concerned?

Yesterday my landlord called me up. I rent a room and pay bi monthly so this happened just a few days ago.

Several of us rent rooms here and as normal I dropped an envelope with cash in the drop box. My landlord went to deposit several of our rents and one 50 dollar bill was flagged as likely counterfeit. I say that because he says that multiple automatic counters at the bank refused to accept it. He said the bank kept it and said they might be back in touch with my landlord. He's been banking with them for years and has done hundreds of cash deposits with them so they supposedly don't suspect him of anything.

He is NOT asking me for additional rent. He's a chill guy and he said he knows it was a mistake and he's fine eating the cost. He only let me know because as he recalls I was the only one that had any 50s in the rent this pay period. He told them he knew who gave it to them but also trusts me. But he did indicate he knew who specifically gave it to him.

I'm a server and so IF it was from my me, it could have been from any random customer OR it could have been paid to me directly from my business. (We are paid out our credit card tips in cash from the safe at the end of each day)

How likely is someone to call me or visit about this? I know reddit advice is always lawyer up and don't talk to the cops, but this is a case where that sounds insanely expensive and absolutely makes me look guilty. (It may be ancidotal but I've only ever heard of one person being charged with this, and it was a guy who paid for a hotel room with 3 $20 bills, one was fake, the front desk called him, and he panicked and ran. But I can't verify that story is true)

Only things I can think to do are get a counterfeit marker and test every bill I have in my possession and if someone DOES come around just be honest and point them towards my work. (Which is 100% where I got it, if it was from my rent) I have nothing to hide, for this or any other reasons, and I'm not exactly concern with police "planting" a whole printing press or something on me. It's not like I even had the bill in my possession anymore.

Is this an actual cause for concern?