For something along this line would be a diagnostic service fee. When you take a vehicle in for regular maintenance and ask them to see if they notice anything they do not hook up any computers to pull codes and it's typically a visual check. Depending on the tech and if they use a lift some will check suspension but if it's a drive through oil drain area they will only look at fluid levels and if any leaks are present.
Call the dealer and ask how much would it cost for a diagnostic fee. If the price isn't high or you don't want to deal with it they may be able to figure it out. One issue, any time some says an issue is "intermittent" I would charge a minimum two-three hours depending on the vehicle. That is because the dealer will have to re-produce the exact issue you're experiencing to properly determine what is going on. Before doing that you should ask yourself if you've gone through your basic maintenance, such as cleaned throttle body, fuel filter which I recall is on the firewall. If this issue is occurring after you filled a tank of gas your gas could be bad or have water. If this issue occurs after you've filled up several times there is no telling but try to look at what conditions you're in such as AC RPM levels noises etc. etc. The more descriptive you can be the better you can get the issue corrected.