Preview render distorting letterforms

When i press/hold space to preview my glyphs files, like 90% of the glyphs presented to me are distorted in this crazy way (See pic) I got concerned when I spoke to my colleague about it and they havent experienced it - Am i doing something wrong? will this ever effect my output? or is it just a bug with apple?

06%20PM

Can you send me the .glyphs file?