AD&D “Slave Pits of the Undercity” (A1): A Glossy Interior?

I’ve got an AD&D module A1 Slave Pits of the Undercity with the cover interior with the same gloss as the exterior.

This A1 is a 2nd print, with the TSR Wizard logo + fixed picture glitches. I thought it might be a owner lamination job but I’m not seeing that – it looks and feels like the outside cover. Seemed odd as the old school modules were mostly no-gloss inside, and I don’t recall seeing A1s like this.

I was struggling to get a photo to show the gloss under my lights, when I realized the glare from the flash would – for once! – be useful. In the main photo, this oddity 2nd is laid on top of a 3rd print A1 I had on hand.