I have -789 RP

I just bought the Demon Vi skin and my RP went negative. I had 1100 or so RP before I purchased it. Now it says I have -789 RP after purchasing a 975 RP skin. Just wondering what is going on.

I think this is just cosmetic. When I select something else in the store the window that pips up says I have 185 RP. http://imgur.com/5LvY1sl