This is correct. It was down to a date issue.
As you should know, unixtime is stored and read as seconds since epoc (crap, when was that, can't remember).
In C, you have to set the size of a variable, 1 size too many for the data you are going to handle, as a null terminator is used at the end, and as such, is part of the strings length.
When the size of the number increased an extra digit in september, it caused problems on some systems.
This was fixed way back, between 1.6.4 and 1.6.5, but was never very well publicised until a few weeks before the bug was due to occur.
A simple upgrade is all that is needed to fix the issue, or placing the following 3 lines at the bottom of your config file
proc unixtime {} {
return [clock seconds]
}
)