Not unusual for spring flowering plants to occasionally throw a few extra flowers at this time of year, just a lucky bonus really.

It's a response to our erratic weather maritime systems. Certain (weather, light, temperature) stimuli are telling your Magnolia plant that it could be Spring. Although the shoots that are flowering now won't have time to set new flower buds for Spring of next year it's unlikely to make much of a difference to the overall flowering show.

The large magnolia in our neighbour's garden has allways put on extra shows following the main flowering.

Indeed Dorjac, that's because of our maritime climate. They tend not to do this in the Himalayas, for instance.

Also the evergreen species - Magnolia grandiflora and it's kin - can and will flower at any time of the year.

Thank you for your comments, nice to know i won't loose out in the spring :)