Oh it smelled weird for 5 minutes but now you are worried?!
Rendering is very demanding compared to other things you do so the CPU got hotter then normal so it could be that some gathered dust just got hot enough to start smelling,without being there and looking at the hardware it's difficult to determine what happened.
If it starts smelling again take a closer look, or whiff,at the PSU area that's the most possible area for something to start smelling, PSU and power cable.