The has been a construction crane in use around the 09L threshold for a couple of weeks now, so depending upon where it was, it could have effected the climbout. A couple of Sundays ago, 09R was being used as the landing runway for the opposite reason, the crane was in the final approach path.
Also, combined with the fact they changed ends and Concorde can be fuel critical, this is probably why 27L was used. There has been more work done on 27L during the nights, so perhaps the "bumps" are better.