Weird phrase showing up instead of comment time / date

One of my readers pointed me to a weird bug that seems to turn the time/date thingie informing you when a comment was posted in a weird string:

[img=http://img32.imageshack.us/img32/864/picture1ntd.th.png]

As you can see it says 1110ij instead of the date. It parses the time correctly. I use the Dutch locale and therefore Dutch time/date settings.

The bug was there with version 3.3.2 and still with 3.3.3. I haven't noticed it myself, since I read comments and react to them in WP's backend. And there everything looks fine. I thought it would have something to do with reCAPTCHA, but disabling that plugin doesn't change anything. It's weird, I cannot find what causes it. Anyone here has a bright idea?

The site affected is http://ingeloots.nl/ where my Dutch blog is hosted, the English language blog is unaffected at http://www.taquoriaan.com