Be concerned if you want to be as they are your chickens.
But most places that have strict bio security plans are for birds or hogs or cattle (veal) that are in close quarter confinement. In the environment even the air in and out of the building is controlled.
If a disease gets started in the confinement building it would be catastrophic to their bottom line.
If you let your birds range pretty much all the bio security in the world just went out the window.
As they will peck and bathe in dirt, eat bugs, snakes, worms, and poop from dogs cats other birds.
As well as grass weeds seed. So unless your yard is bio controlled your birds are exposed to who knows what. Did the previous owners have duck, geese, turkeys, cows, goats, a bird feeder or chickens. Because some diseases stay viable in the soils for years.
I raise my flock as survival of the fittest. I want them exposed to as much as they can be to build up resistance or tolerances to things.
I like to goto auctions, swaps, and poultry shows. So if I had to follow bio protocols I would take a lot of enjoyment out of the birds I have.
So do what makes you feel good about your neighbors flock and yours. Just giving you some inputs from a different perspective.