Mine does this occasionally too. It's fine after the engine has been worked for a short while. If you manage to solve it come back and let us know.
Another suggestion I've had from a mechanic who seemed to know a lot about Land Rovers and built competition vehicles in his spare time is that it could be an injector sticking, and once it got warm it freed itself. This sort-of makes sense, because the smoky start ups are less noticeable after I've put a bottle of injector cleaner through it. It's never been bad enough to merit major investigation and the engine still seems happy otherwise.