Lightroom 4, correcting chronological mistake?

We just took wedding pictures with two cameras. Uploaded all the pics into lightroom 4, and clicked organize chronologically. Then realized that one camera's clock was about 15 minutes behind the other, so all the pictures are shuffled better than they do in Vegas. Are there any easy fixes here? I know I can edit the metadata for the pictures individually, but we're talking about editing around 1, 000 time stamps.
Thanks for any advice

If it matters, the cameras are a nikon D7000 and D600, a variety of lenses switched throughout the day, and the latest firmware update for LR4 has been installed

I don't have lightroom but this might help