I traveled to WDW in January and April this year and I have a full (three trading bags and then some...LOL) in a carry-on suitcase. I always get this look from the scanner operator and then I get "Oh, its you again" and "I thought this suitcase looks familiar"...just a quick check of the pin bags inside and I am on my way.
Only had one issue about a year ago with a person at the check in in the Sanford, FL Transmeridian Airlines desk that tried to force me to check the bag. She first told me that we had too many carry-ons (we had one each) and then she tried to tell me that the bag was over weight (it was 35 lbs.). I informed her that it was worth quite a bit and if she would personally be responsible for the value (I have over 350 trade pins) I would be glad to check it with my luggage. After that she went to the TSA supervisor and had me designated as a "secondary screening" candidate and I got a 30 minute search and screen before being allowed through the security check point.
Lets just say that we won't be flying on TMA in the future!