T43 P4-2.13 CPU core thin foil??

[Jefferson]

When I took apart my new-to-me T43 for thermal repasting, I noticed a piece of square-shaped thin foil that covered the CPU core.

I was in a hurry so I removed it and applied thermal paste, as i've done many times in the past. But now I wonder if I should've left it alone.

It's thicker than household aluminum foil but much thinner than copper shim and it peeled off like foil.

Does anyone know if it was factory-installed?

The way it was applied seemed like it was factory installed but i'm not sure.

[H-Atkinson]

Neither of my T43p units had one of these.

If the thermals seem fine, then I would leave it out.