Ephraim, who has been farmed out on loan to Charlton until January, admits Hoops boss Warnock shocked him when he left the midfielder out of the 25-man squad at the end of August.
He said: "After working so hard to get to the Premier League with QPR, I wanted to stay and it came as a bit of a surprise when the manager made the decision he did.
"When that happened, I knew I had to move on and I chose Charlton because I knew some of the staff from my days at West Ham.
"I enjoy training here like I haven't done for a long time and I have a smile on my face again. Hopefully that can continue for the next six or seven weeks and I can play a big part for Charlton.
"I am concentrating on having a great time until January 3 and we'll see what happens from there."