No, it's not power creep, for the reason mentioned above -- you can only get one skill power through the feat. But even that issue aside, I think that Stirring Speech is the farthest thing from overpowered. You really underestimate the "when they're not bloodied" requirement. If a fight is easy, there's no need for +1 to hit. If a fight is challenging, the benefit will frequently shut off at the most inopportune moments.