Only three backups preserved!

After running the 7.x-1.1+2-dev (2012-Dec-25) version for about 10 days I still have only three backups in my list. Prune keeps deleting the fourth one every day.

Right now I have backups for Thursday 3rd, Friday 4th, and Saturday 5th.
However, there's still the .gz.info file for Tuesday, January 1st!

Every day I see the following:
on 3pm B&M creates a new backup
on 4pm Prune deletes a .gz file (says "Deleted 1 backups.")
on 5pm Prune deletes a .gz.info file (says "Deleted 1 backups." again)

12/30: 2012-12-28.mysql.gz, 2012-12-28.mysql.gz.info
12/31: 2012-12-29.mysql.gz, 2012-12-29.mysql.gz.info
01/01: 2012-12-30.mysql.gz, 2012-12-22.mysql.gz.info
01/02: 2012-12-31.mysql.gz, 2012-12-30.mysql.gz.info
01/03: 2012-12-27.mysql.gz, 2012-12-27.mysql.gz.info
01/04: 2013-01-01.mysql.gz, 2012-12-31.mysql.gz.info
01/05: 2013-01-02.mysql.gz, 2013-01-02.mysql.gz.info

This leaves me with the following files:
2013-01-01.mysql.gz.info
2013-01-03.mysql.gz
2013-01-03.mysql.gz.info
2013-01-04.mysql.gz
2013-01-04.mysql.gz.info
2013-01-05.mysql.gz
2013-01-05.mysql.gz.info

Having deleted a matching pair of files today, I'm now manually deleting the odd 2013-01-01.mysql.gz.info file and will keep watching how this develops further...