More so than that, on older Nissans and Datsuns it was a sign of wear in the box. As all the clearances open up it would allow the driven gear for fifth to run at an angle instead of nice and square and that wears the dog teeth on an angle. Once it gets bad enough the thrust created by the wear will just push it out of top.
The biggest cause on the older boxes was the mainshaft nut coming loose and allowing all the thrust clearances on tha mainshaft to open up, not sure if they got around that problem in the later ones. I know that compared to the older ones the more modern boxes have a flat bearing under the nut and washer where the old ones did not.