I have a hard time believing this is indeed Agave guadalajarana. I think all three pictures here are of the same plant or of a similar plant at the UC Berkeley Botanical Gardens, and its way too green for A. guadalajarana and the leaves are not the right shape and how they carry the teeth, at least for any A. guadalajarana plants that I have seen.

Check this link out and let me know what you think:
http://www.agaveville.org/view...

I suspect this plant or these plants are all examples of A. bovicornuta or another similar Crenatae agave.

Could the difference be because it's grown indoors without any direct light?

Not impossible, but I think in this case highly unlikely. The picture that is also from UCB Bot. Gardens, but not posted by you, shows the plant with yellowing leaves - I assume that even if it is not the exact same plant that at least it is a sibling grown under similar conditions. The yellowing is usually a response to too much sun, A. guadalajarana loves the sun, A. bovicornuta and cousins do less so and show that kind of typical yellowing when distressed. Maybe it is an A. guadalajarana x bovicornuta hybrid? It is hard to argue against a label put on in a botanical garden, but experience tells me that even they get it wrong on occasion.

Well I just moved the three into the generic agave entry.