Why did this happen?

So this was my second time headed into this liquor store, first time I was there my IDGod CT worked flawlessly.

I walk straight to the rum, grab a cap and head to the counter. The same cashier that checked me out last time is working. I get out my ID and money and he picks up my ID and immediately pockets it and tells me he knows my ID is fake.

I'm well dressed and very confident as the ID worked perfectly before, what the fuck happened? The first time he scanned my ID and it worked and he didn't make any comments, he had a completely different attitude towards me than last time.

Thoughts?