I just don't necessarily think it means something bad.
I went out for dinner with my dh last night and yanked a big black hair out of his nostril (because romance, clearly, is dead). Had we been paparazzi fodder, this could have made an interesting shot especially as he would have been caught looking momentarily tortured.
I sincerely hope Nigella isn't being throttled or abused by her husband, either in private or public. I just wouldn't assume the worst from a few pap shots taken over the course of a few seconds.