clutch Master cylinder to Throwout bearing hose

[500H V10]

I'm replacing my clutch, throwout bearing assembly and master cylinder. I had a small O ring stuck in the hose where it connects to the throwout bearing pipe. Does anyone know where this O ring came from???
I bought my Truck new so it's never been touched before. It looks just like the O ring inside the master cylinder where the hose connects. The O ring is still in my master cylinder tho. Could the assembly line have screwed up and accidentally put one inside the fitting to the hose??? Seems unlikely to me but its the only thing I can think of.

 

[trussman]

Is it not the o-ring that should be on the outside of the male end of the line?

 

[500H V10]

Yes its a small one . It looks just like the one that goes in between the 90 degree fitting and the pedal master cylinder.