When you select the "File > Open All Recent Files" option, the order of the tabs will in the reverse order of their last opened state. I work around this by opening NPP, selecting the aforementioned command, select "File > Close All", and then reselect the offending command. This is fine, I guess, but certainly an unexpected UI behaviour.
Anyway, it's certainly...
2009-07-13 23:49:31 UTC in Notepad++