Unexpectedly loud creaks from my attic floorboards when the heat kicks on

I just moved into a 1920s bungalow, and everything is charming except one thing: whenever the central heating starts up, the attic floorboards creak loudly like someone pacing around up there. The noise isn’t constant - it usually happens within the first 10 minutes of the heater running and then stops. I’ve checked the attic and found nothing out of the ordinary (no critters, no loose floorboards visible). I’m guessing it might be related to the wood expanding and contracting with the heat, but I’m worried it could signal a bigger problem or damage over time. Has anyone else experienced this kind of creaking linked specifically to heating cycles? What’s the best way to diagnose if it’s harmless expansion or something needing repair? Also, are there any quick fixes to reduce the noise without ripping up the floor?