Not sure why, but this is happening now in my gallery. I'm getting numerous emails from members telling me that the email they get contains an invalid link.
I have version vbadvanced_gallery_1_0_1_10339 installed.
I was told by a few mods who were keeping an eye on when/why this was happening and they said it was usually only if someone replied to their new post within the first 15 minutes or so (can't say whether or not the time is accurate). After it's been there for a bit, the subscription emails come through fine with the correct link to the photo.