Thermal cameras see IR, metals, especially bare metals have a really low emissivity, meaning that they radiate very little IR and reflect the rest. (what the camera sees)

Think of it as a mirror, aluminum foil for example has emissivity of under 0.1 (it's a scale of 0-1, 1 being 100% radiating/absorbing) so only 10% of the total possible energy is being radiated and 90% are being reflected.

What you're seeing is a combination of the reflected IR + the radiated IR.

So the surface reflected is likely what you're seeing + the housing.

Take an aluminum foil and literal look at yourself with the camera. Foil is basically a mirror for IR as a glass mirror is for white light (what we see)

Emissivity is affected by material/color/surface. To get a better reading you want to paint it with a black body color, something black with a rough surface and very little visible shine (matte black)