Retina MacBook Pro running very hot?
100C (212F) is the thermal limit for the intel processor in your machine. The computer will shut itself down to prevent damage if necessary. This means a sustained and significant increase above that threshold. Not a spike. The temperatures you report are within normal operating temperatures based on the usage. Tips, moving forward:


Keep your Firmware up to date.
Make sure the back vents are not covered or obstructed in any way. This ensures proper ventilation. 
Don’t manually adjust the fan settings, or the like, using applications like “iStat Menus." The firmware in your machine is very good (better than you, or I, or any human being) at keeping the machine cool and dissipating the heat produced from CPU/GPU intensive processes. 


Bottom Line: This is completely normal behavior and nothing to worry about.