Do I deserve the warning I'm about to get?

At my university in Wolverhampton, the cleaners come round our halls 3 times a week and clean the shared kitchen and bathrooms and vacuum etc. The problem is that for the past 2 weeks, my flatmates and I have left washing up out continually on the kitchen sink, and we had a warning last week that if we didn't clean it up, the cleaners would take it all away and charge us to get it back. We thought sod that, and left it. Today anyway, the cleaner came back and started boxing it all up, and I came out of my room and started shouting 'put it back!', and she just went you'll have to take it up with the warden. Admittedly I started getting quite abusive to her and saying, no wonder all you've ended up as is a cleaner on minimum wage if this is what you're like, and 'I'd hate to be in your lowly position, cleaning up our **** day in, day out'. I could tell I'd quite upset her when she left (with our stuff), but I thought that was the end of the matter. She reported me to the halls manager though for being offensive and derogatory, and now I have a meeting in which I will probably be given a formal warning. Was that cleaner right to do that?