I've seen this before in a different ad group and asked G about it, but got a blunt response that the stats are clean, that there had to be a real spike. The keywords that would have caused it are for a mundane clothing category, nothing that has been in the news.
So does anyone else see these occasional spikes in impressions?
I have personally never seen these stats to be very-wrong, but I would contact GAW if you think this is.
This is a pretty common phenomena. Often the rise in impressions is very real, clicks/conversions may or may not correlate to these impressions spikes as people reading news are often in a different mindset than those looking for some specific info.