Hey guys. I have a 15" rMBP 2.3GHz Late 2013 with Mavericks 10.9.2 and when I turn on the Macbook the startup chime or sound is completely gone. Should I be worried? I also tried resetting the NVRAM and it's not the solution. It does the chime but when I reset the computer again after resetting the NVRAM it doesn't do it anymore.