Unknown person deposited $217 into my Venmo account

I'm not sure if this fits for this sub, but couldn't think where else to put it.

A man who I don't know just deposited $217 into my Venmo account. I got the email from Venmo and immediately thought it was a phishing scam so I didn't click any of the links or anything in the email. I checked my account through the actual app and saw the transaction was actually made. Am I being scammed somehow? If the guy made a mistake I want to send him his money back. Is there anyway for me to be scammed if I just pay him right back when/if he asks for his money back? I don't intend to keep somebody's money and would like to make this right.

I've just messaged him and am waiting to see if he responds.