Timed Practice Didn´t recognize Spanish

[Usagiboy7]

Windows7/Firefox
Using the duolingo-dark-2 style (which is why the screenshot is in dark colors):
http://userstyles.org/styles/90721/duolingo-dark-2

Timed practice did not recognize my sentence as Spanish:
"mi primo hizo una revisión del documento."

Here is a screenshot:

[kristinemc]

Did this happen just once in the session?

[Usagiboy7]

Yes. I didn't notice it happen again after that.