That is probably an immature Green Stink Bug. They are not usually serious pests in Michigan, but we have been having quite a few reports of them this year. They spend the winter as adults and they will probably leave your plants to find a sheltered location somewhere else before winter hits. I think if you inspect the plants well and remove plant debris and leaf litter from the surface of the soil in the containers you should not have to worry about bringing them indoors with the plants.