Aita

So I'm really ticked off and need to both vent and ask if AITA (am I the @sshole). We have new neighbors in our building that haven't bothered to introduce themselves. One of my neighbors went downstairs this afternoon and found his washer being used (all units have their own washer/dryer hookups in the basement of our building). He politely explained to the new neighbors that each unit has their own hookups, told them which belonged to who and pointed out where their washer/dryer hookups are. He made them take their unfinished wash out so he could do his laundry. They waited until they thought I had finished my laundry and then proceeded to use mine without asking. I didn't say anything to the new neighbors but took their clothes from my dryer and put them in their laundry basket. Started another load of wash and messaged our landlord to complain. Who does stuff like that when they not only didn't ask permission, but haven't even bothered to introduce themselves first. Did I miss the memo that it has become acceptable to use someone else's belongings without asking? And AITA for just taking their clothes out of my dryer without saying anything? (Personally I thought my response was more restrained than taking their clothes and throwing them in the dumpster considering this was not a misunderstanding on their part but intentional.)