Was EVERY kill command 20 focus? Are you able to do it today, after logging off n' such? I just kinda browsed through the talents and I don't see anything that would cause that...
To add: Killing streak only reduces the cost by 10 with 2/2, bringing it to 30 focus, not 20. Only thing I can think of is you're using BW while using KC.
now, usually, it is 40 focus. but thanks i do believe it would be the talents in killing streak. i remember it was in a battlegrounds when we were flattening peeps, and i am BM.