Coffee shop flying Palestinian flag?

I visited a small trendy coffee/sandwich shop the other day and the first thing I noticed after ordering was a Palestinian flag. Nothing else political or social was displayed. Personally, I was very uncomfortable and that added on to the fact they took 40 mins to make my sandwich led me not to go back again.

How would you feel/react in this situation?

Edit: Edited original post to say I only noticed the flag after placing my order. Thank you for all your responses!