buffalo grass in winter

HI all,

I had soft leaf buffalo laid last year and this is the first winter its
had.....about march or april I top dressed it...filling in holes etc and
giving it a 'feed' for the winter months , or so I thought.

The grass has gone really dark with purple blades etc.....not very
attractive at all..mind you its not growing either so thats a plus :-))

Anyhow I'm wondering if this is normal or did my top dressing before winter
do something to it.