Sometimes magnolia will produce flowers on new growth out of season in late summer or early fall. It may be due to the odd warm winter we just had. Most magnolias in the area had their flower buds nipped by frost this spring and so never flowered. This left the magnolias with a lot of extra energy which it may be using for this out of synch flowering effort. Hopefully we will have a normal winter this year and it will get our plants back on their typical cycle.