Early Glassfiber Vitra DSR (Cracked)  

I recently lent this vintage DSR to one of my roommates, when it came back I noticed a crack...bummer
No insults were made since I could not be sure it was not there before, and because the shell is in (visually) really impeccable condition I never actually paid full attention to any cracks (they were not apparent at all), it was the first DSR I bought and the seller did not mention any repairs made to it either.
Examining the chair after discovering the crack, I noticed that on the inside it looks like it has certainly been redone in the past. Any recommendations on what I should do? How serious is this? I have certainly seen worse cracks, but then, it being my first shell I would really love to see it last a long time.
Also: I'm pretty sure it is an early Vitra production, any thoughts on the value/rarity of those compared to HM/fehlbaum? I don't see them often!
Thanks,
Mr Paul
edit, hopefully fixed the photos now!!