I had to change positions at my work

i work at this bar place at the airport. I've been there for a few months. I applied for the dishwasher position but they decided to put me in front of the restaurant to give me more hours as a busser and I also served people drinks. last week I was told that because I didn't have a liquor license I couldn't be in the front anymore. what's odd is that it took them months to notice that or say anything about it you'd think that they would have said that right away when I started working there or something. all I did serve the drinks i didn't actually make any of them which is good because I would have messed it up because I don't have experience doing that and would have no idea what i was doing lol