Did you not read the whole thread? OP has the video from their car that shows that they did not cut the officer off. The default assumption of police on July 4th in the USA is that everyone is driving drunk. Probably because they're often right. But not always. And cops can get pissed when you don't fit their expectations. Pulling you over, and not being able to write a ticket to you, can be an affront to some cops. They need to fill that ticket book to get their bonus! j/k I don't think they get bonuses, but some police departments do illegally set quotas that officers must meet or face disciplinary action.
Edit: How is OP lucky they didn't collide with anything. It's like you've never used Nav on Autopilot. Auto Lane Change has NEVER caused an accident. It may seem like it's acting funny when it swerves back into the original lane, but it always has a reason. Hell, I was driving once, car started to change to the lane to the left of me. I see a car coming up at high speed. I instinctively moved the wheel to return to my original lane, and assumed I have shut off autopilot. Except the cars motion mirrored mine exactly so my steering wheel movements didn't produce enough torque to cancel AP. A few seconds later it completed the lane change safely. The car's #1 goal as stated by Elon is "NO COLLISIONS"