Some files are excluded during check by a restricted files or pattern list, but there are some more files that need to be excluded for the access time check. In our case there are .sha1 files that are created on download. And maybe sources and javadoc will not be access, too, depending on the maven settings (e.g. if the repo is used on build machines).
See: About Checksums
To improve this feature, some more pattern/files should be excluded OR it could be better to check only the file with the latest access date (more complex)?!