Files don't randomly disappear. Downloaders can set the date of downloaded files to the time the server reports.
OpenBSD then deletes them because they are old. Don't use /tmp for long term storage. It's temporary. The clue is in the name. Matthew ps. as a general rule if something has been around for 50 years, is used by millions daily, runs a sizeable chunk of the internet, and it appears to be broken, you're probably holding it wrong.
