Ask HN: Anyone seeing a significant increase in yahoo/bing traffic?

Normally most of the search traffic we receive is from Google however the past two days we have had 10 times more traffic from Bing/Yahoo than we normally do. All of this traffic has a bounce rate of 100% and spends 0 seconds on our site.

It appears to be a spider however this data is from Google Analytics and I don't think that a spider would be executing Javascript. Is anyone else experiencing the same thing?