jeff.f,
One further point if signs again appear anywhere on Common Property. Remember that whilst your O/C is fully empowered to remove them, the signs are the property of the RE Agency who had them placed there.
In those circumstances, as EC Secretary I always e-mail the RE Agency concerned to advise that their signage has been removed and why, and to advise that it will be held for seven (7) days for collection by them, after which time it will be disposed of.
Maybe ask your Sec. or Strata Manager to do that, just to cover your bases!