Ok to explain this a little better these were not complete strangers but neighbors who we somewhat know but the dogs have never met before.
I agree that I should not have let Brock go up to them and avoided the situation all together. I guess I wasn't worried about him going up to the dogs because they were both older and small non-aggressive breeds so I just assumed they would sniff and be on their way. Assumptions always get people in trouble though.
On a side-note we have not seen them using our yard as a walking path since that incident, heh.