I have had a problem at Elite check in flying YYZ-LAX this year.
I had a YYZ-LAX-PSP trip booked for ~$250 and planned to ditch the last leg. Booked last minute and YYZ-LAX alone was ~$1500. even though it was business money I didn't want to waste it for no good reason. Accountant sitting next to me wasn't thrilled that I paid 250 and he paid 1500.
Agent looked at my Roll aboard. Said it looked heavy. made me weigh it then demanded i check it. I was only 5-10lbs overweight and started removing items to carry them by hand. of course I couldn't check my bag through to PSP when heading to LAX.
I got SSSS on my ticket after that. Random I'm sure.
Now I try not to bring heavy carry ons to checkin counter or just OLCI. Never had a problem at the gate.