Well your thinking most likely is correct....if you are feeling the heat it is not being held in the engine.
Did you change something else....like the muffler or jetting or the air cleaner that may have also contributed to the way the engine may be running? Or did you change your route that requires you to spend more time in traffic? Have you cranked your idle speed up?
Oh yes. I have never ridden a stock Savage. Mine was bought as a barely running heap. So silencer and air filter are non standard. Runs ok but pops a bit when throttling off. Some say this means it's lean, others say it,'s rich and igniting un burnt fuel in the pipe. Another conundrum perhaps.