Info from a source close to the EADS Historic Flight, as reported in Flugzeugforum.de:

Both landing gear legs were down and locked and indicated as such, but one of them folded on the rollout due to an unnamed u/c component (not the same one as in “Red 7”) failure. All damage is repairable, but it won’t fly again this year and will return to Manching on a lorry.