I reckon the dogs over the fence have alot to do with it as well. The flies that our dogs food attrachts often rest on the plants under the veranda leaving fly shari all over them. I guess the plants don't enjoy it and need occasional cleaning.
Definatly nothing to panic about but would be good to find a way to reduce them. Try googling fly repelant plants. Not sure how good these remidies are but basil is one. Hmmm basil
It's too bad your in such a hurry cause the stories I could tell you, Bushels and baskets of stories, hole crates full of stories. But if you can spare a moment I will tell you one story.