Is it disrespectful to use a product before buying it?

I was in a corner shop buying a few things, one of them being a bottle of water.

There was quite a long queue, and I was really thirsty - I opened and drank from the bottle of water (I was obviously still going to buy it, so IMO makes no difference).

The shop owner really wasn’t happy with me, said other people would’ve called the police on me etc.. thought it was very over the top.

I still paid for my stuff and left but he accused me of being disrespectful, and tbh I think it was him being disrespectful…

Am I really in the wrong?!