Is this a scam? Selling off of Facebook Marketplace

Hello! I am selling an item on facebook marketplace. A woman messaged me being very interested in it. She said that her son could meet me tomorrow morning to pick it up, which was fine by me, since her schedule and location wouldn't have worked. She said that she could Zelle me the payment right now. I received a text from her, the particular that indicates that this is a scam to me is this part of the message:

"Zelle: (redacted) sent you $15.00 & it's ready now. Reply YES to accept STOP to cancel these texts."

It sounds and looks a little fishy...if it was truly a Zelle transaction, I would've just gotten a notification that someone had paid me, right?

Is this a scam, or no? Just wondering if I'm being paranoid or not.