You said not losing "any significant amount" ? So it is losing coolant? And if you smell it on the right side to my knowledge the right side is heated air exhaust by way of the fan and if that is so I bet your coolant pump is starting to fail. The pump might be slightly less efficient as the shaft seal fails letting the impeller wobble slightly with flow improving with increased rpms when you get going. You can pull that bulkhead access cover and check less than 10 minutes. It's a pretty basic DIY to replace but requires a few special tools and the vacuum fill device.