Weird digits after URL in Google Webmaster tool

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Hi

Noticed a strange thing today in Google Webmaster Tool. On a 5.6 site, some URLs have now a string added after the trailing slash. Such as /infographie-sur-le-contenu-redactionnel/1347133639000 where 1347133639000 is really totally out of the blue. Of course, GWT sees a 404.
There are 15 pages like this ashttp://screencast.com/t/dvzhduei... and it started a couple days ago. I think it was days after Wufoo was installed and I dont see any reason why it would the origin of the problem.

Kind of strange, and clearly not good in terms of SEO.

Here's the installed blocks

# Version Concrete5
5.6.0.1

# Paquet Concrete5
AddThis (1.0), Automatic Email Obfuscator (1.2.3), Disqus Comments (0.4), eCommerce (2.8.5), Expand / Collapse (1.2.1), Extended Form (2.6), Facebook Like Button (1.1), Fancy Image Links (1.3.7), Formigo Containers (1.0.0), Guest Blogger (1.0.5), Html5 Video (1.0.2), Internationalisation (1.1.3), Lightboxed Image (0.9.2), Mail Monkey (2.0.0), Manual Nav (1.2), Payline (1.0), Paypal Cart System (1.0), Pro Blog (7.0.1.1), Responsive (1.0), Rigid Light - Theme (2.0), Suivant & Précédent (1.02), Tweetcrete (1.6.5), Wufoo Forms (1.0.1), YouTube Pro (1.0.5), Zoom Image (1.0.3), Zoom Image Dual (1.1).

# Remplacements Concrete5
blocks/form, blocks/formigo_containers, blocks/pd_responsive, languages/fr_FR, models/attribute

Anyone seen this error before ?

witwag