auto trans problem

hi everybody, I have a 03 gt tibby, and it has a trans issues I guess, this ploblem just happen when engine is cold, when I change into R from P it takes like 4 seconds to move, it happens the same from N to D, the fluid level is ok, the thing is that this didn't happen before, it used to change inmediatly, so that makes me thing it is a trans problem...

any sugestion???

thanks