Hard to say...I too struggled with this question, and ultimately decided not to bring it up because the school's probationary status seems largely in the past now. Check out this article about it:
http://www.washingtonpost.com/wp-dyn/content/article/2010/02/03/AR2010020303788.html
Near the end of the article, you can read some of the specific measures taken by GWU to escape probationary status. Plus, by the time we'd matriculate here, the original probation will be 5 years old, and the school will have been out of probation for 3 years. And looking at GWU's match list, MS4s seem to do just fine matching (at least, they don't seem to encounter
obvious difficulty). These things were sufficient to allay my concerns and forgo asking about them during the interview. I would have been more inclined to ask about them had I been applying in 2009 or 2010.
Also, I don't think it would be "interview suicide" to ask if you did so in a non-accusatory way.