Yes, it has happened to me. It was a year or two ago so not the current OS or AP version. I seem to remember it was a problem with TIFF files, not JPEGS. I think a couple of other people had seen this, you may to search these forums to find anything. I can't find details after a quick look.
I'm sorry there is no answer. I stopped adjusting the date using Aperture. I now use PhotoMechanic which is reliable for any metadata work you need to do.