heh, why never mentioned bout the location of the chair/sofa?
In public area or common corridor izzit?
If its really along the corridor or some spot outside the house, heh, most likely its that someone complain to town council and thus they have to take action.
There are cases of ciggie butt thrown on sofa along corridor or staircase landing and result in fire. Its also for the safety of residents. Spare a thought for our neighbours