Canon 40D + 24-70 took a tumble... now getting soft pictures @ 70mm

[mmodica]

The other day, my 40D and 24-70 took a tumble onto concrete from a height of about 5 feet. Everything seemed mostly fine at first. The hood was cracked, which I glued back together, and one part of the hot shoe was bent, but I just bent it back.

Then, after reviewing some of my shots, it seems like ones shot @ 70mm are slightly soft and show some halation compared to ones shot at 24mm, and compared to what I'm used to getting with my copy of this lens.

Any suggestions? I'd hate to have to send this guy out for repair, since its my primary lens (I no longer have my 17-55mm f/2.8), but I'm concerned with this apparent change in image quality...

EDIT: I have only done tests wide open, but I'll try shooting some shots stopped-down and see if there's a difference. I'll also try manually focusing as well to see if its a focus accuracy issue. Unfortunately the 40D doesn't have MFA though so I'd have to send it somewhere to get it callibrated.