I rooted my phone, but I never flashed the ROM and I never flashed the recovery, then I unrooted it. Can you tell its been rooted?
The short answer is yes. You should make sure your bootloader is locked by executing fastboot oem lock in your command line while your device is in fastboot (Home + Power + Volume+ for your specific device). Once your bootloader is locked it will be as if you never rooted your device. Once this is all done, you will regain your warranty which would otherwise be voided if you had left the bootloader unlocked.