The altercation did indeed happen.
At the conclusion of WrestleMania 34 in April of 2018, Brock Lesnar defeated Roman Reigns to retain the WWE Universal Championship. A few hours and the following days after the show, there were a rollercoaster of reports which entailed that there was some sort of altercation between Brock Lesnar and WWE Chairman Vince McMahon culminating with Brock throwing the title at Vince. There was never visual proof of this happening along with various stories concerning how the altercation unfolded, but last night after the Royal Rumble pay-per-view went off the air, WWE aired it's WrestleMania 34 recap mini-documentary on the WWE Network.
Once Brock walked back behind the curtain, he tossed the title at Vince McMahon and Vince responded, "Hey a*shole" and that was the end of the clip.
If you're looking for a throwback review here on Fightful, click here to watch our post-WrestleMania 34 review which features a number of members from our podcast crew.