What oil were you using ?
It's kind of odd that would happen without any prior noise. I'm also sure you were not expecting it so you were not intent on listening to the engine sounds.
Yes, do let us know...
175,000+ miles, 5/20/12 new ej257 short block, 8/20/11 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. Also CHECK YOUR OIL, these cars use it.