Should be flowering = no, can it = yes.

Pruning should be avoided as Magnolia just does not tolerate it and will sulk and may not flower next year. if you really need to keep it in check then do so but you make not get flowers. Wait till late autumn/early winter - say December.

many magnolias will throw the odd flower out at this time of year, so nothing unusual.
as for pruning I dont unless it gets out of its space. I have pruned after flowering in the spring.

Don't prune magnolias when there is a threat of getting frost in the cuts. As SBG says, after the spring flowering is probably the best time