Interesting. The cover remark is especially telling: had you gone into the center route at all? I might not have accounted for people briefly going up that way, and then returning to the normal alley path (though I'm fairly sure I did, and patched it at some point). That said, while I appreciate the report and will keep it in mind, I probably won't try to hunt down this particular bug for now, as it seems like an odd edge case (as evidenced by the fact that the game's been out a while and this is the first report of something like this in quite a while), and one that wasn't TOO hard to fix. If it KEEPS cropping up for you even after using the other save or on other playthroughs though, let me know, and I'll keep an eye out in case I get similar reports.