Aviation Week revealed that the start of final assembly as well as the first flight date for the A350-900 has slipped by three months. Airbus is not slipping the entry into service date and it is still unclear if there are any other possible strains to the schedule at this point.
Aviation Week attributes the delay to more time needed to finalize some of the detail design of the aircraft as well as other areas that needed more time. Final assembly is now due to start at the end of 3rd quarter 2011 (as oppose to end of 2nd quarter of 2011) with first flight due to take place during the third quarter of 2012 (vs. 2nd quarter of 2012). EIS is still scheduled for mid 2013.
Airbus is still struggling with weight issues on the airplane and have embarked on an aggressive weight reduction effort. Still it is tool early to say that the first delay is any indication of a trend of delays that may occur. Here's Aviation Week's article:
Airbus Delays A350 Final Assembly
The Aviation Week article confirms the belief of many in the industry that the A350 will be inevitably be delayed though there is still much discussion over the length of the delay. The fact that delays are being taken now as opposed to later in the program is not a good thing. Here's a an article by Saj Ahmad written about 3 months ago warning of the delays to the A350:
Airbus A350XWB Weight Grows As Pressure On Schedule Mounts