[Paddysmom]

Go meet them, meet their dog and make friends and then ask the people if their dog is "dog aggressive" If they say no, then have a very supervised "meet and greet". If that doesn't go well, then tell the people you walk your dogs every day and what do they suggest? Then carry mace.

Yep... do these things that Pat suggests.
Was it a "beware of dog" sign? At least they have given a "heads up".