Have had experience on this pin before, we had different problems with the display, but it was not the power. I measured 4.88V on the DMD connector (4.92V on the PSU), but the problem was in the chip driving the display. Power was good, even at those voltages.
Best thing you can do now is checking the voltage difference on the connector on the display and on the connector on the PSU, and if there's a large difference, you probably need to upgrade the connectors/wiring. Other than that, if it still works, why change it?
