Yes, I fell over the some 20 years ago with the same result. It seems that cron does not make sure that all conditions for the day match, so you may find that it runs every day between 15th & 21st...
That means cron treats the dom field and the dow field as OR.
To make an AND, you put one field into the crontab and make your script exit on the other condition. For example
45 4 * * 0...
Yes, it is a known issue, they updated it yesterday/some days ago. The same way as with other security patches - you download APAR (the link is on the site), untar it, install using emgr.