Czech beer

I went to the liquor store looking for some Polish beer. I couldn't find any in 6 packs, only 12 packs. I didn't want to gamble on that much beer, so I bought some Czech beer instead. Staropramen. Not bad, but I think it sat on the shelf too long and had started to sour a little. There was some dust on the bottles. I'd say it was a good beer 3 weeks ago.