Straightening algorithm change in A3 update?

Question

I was playing around with some old photos in Aperture today and noticed some weirdness. First some background. The photos were taken with my old Digital Rebel and are jpegs imported into Aperture. I imported them some time ago, probably Aperture 2. At that time I did some adjusting and was reasonably happy with the results. Today I was browsing through them looking for photos that might be suitable for converting to B&W and noticed that quite a few of them had a strange pattern across the bottom.
The pattern appears as vertical anomalies on the bottom, which is more pronounced towards the side. A bit hard to describe, but it looks like the bottom pixel was turned into a short vertical line, with each pixel along the bottom of the photo doing this. The original jpeg is fine - no weirdness at all. In order to get rid of the anomaly I had to "revert to original" at which time the problem went away (together with any edits I made, of course).
I did some nosing around and it turned out that every one that I had applied the straighten tool to had the problem. In fact, the more the straightening angle, the worse the artifacts. In the artifact, the length of the vertical "line" depends on the angle of the straightening and the all the lines form a 'wedge' along the bottom of the photo, showing how much I had rotated the photo. Unchecking and the re-checking the straighten brick cleared the problem and restored the straightened picture. I looked some more, and the same problem exists with the 50D raw photos, so it doesn't appear to be due to being jpeg. Ditto for managed vs. referenced - same problem. The only other thing of note is that I upgraded the video card to a 5770 a few months ago, but it's hard to believe that caused it.
Last try was to first repair and then rebuild the Aperture library, neither of which made any difference (straightened photos still showed the anomaly).
So, my conclusion is that the straightening algorithm in Aperture changed at one point and the problem with earlier straightened photos is a reflection (so to speak) of that change. I'm not sure which version changed things, but at sometime on or after A3 the problem appeared. Anyone else seen this? Easily corrected, albeit a bit laborious with all the manual labor involved, but also bit irritating since there doesn't appear to be a way to tell Aperture to 'uncheck and recheck any straightened photos'.
- Ken

Answer 1

Thanks for both of the suggestions, but neither one worked - no change to the previews. I went through the library, and everything taken on or before August, 2009 showed the artifacts, while photos taken on or after May, 2010 are OK (the interim period either had no photos or no straightening).
I'm pretty good about loading and processing pictures once I take them, and I also update Aperture fairly soon after a new release comes out. The data suggests that there was a change in Aperture that occurred between 8/2009 and 5/2010 that brought out the issue. I would never have known it except that I went back to some earlier photos to use them, which was when I found the problem. I can't imagine that it's anything I did to cause the problem, especially since the photos with the problem were fine when I initially worked on them.
- Ken