All jailbreaks are now traceable via apple stores

when and if they plug your iDevice in for diagnostics it will give them a full log off all events, including jailbreaking.

If you device is new and in warranty don't jailbreak

my iPad has now just turned a yr old and is jailbroken, but my 4s is just as apple intended (abet it's going back for the 3rd time as it constantly crashing)