new 24-105 plus 6 D an already a problem

I just received my 6D with the kit lens 24-105. Without stabilisation i took some tests shot at 1/8, 0.4 sec, 1 sec, and they are all sharper than with stabilisation. And it's very clear, i don't need to do a full zoom on the pixel to see it. I've taken 3 shots of each and always the same result. At higher speed , like 1/40 same thing.

Also i try to wait longer half pressing the button before taking the shot and same thing.

Should i send it back to canon or do more tests ?. It's not my first lens with IS, I did some test with my old 28-135 IS and everything was normal.

Are they anyone aware of a bad batch of 24-105, with serial numbers ?