Curiosity about uptime

Hi,
I have a curiosity about uptime, I have a Flint 2, but I remember this was happen also in Flint.
Sometimes happen that the uptime in the web UI, command line, and iOS application is different.
In this moment I can see ~6 days of uptime from https browser and 36 days from Command line and iOS application.
Can someone be able to explain this??
Screenshots: