Interestingly, my iPhone 6 on Verizon's LTE in the US is running on IPV6. Fascinating that my campus computer is behind the times, relative to my cell phone.
It's interesting too that you mention a campus computer in comparison: most American Universities were early adopters and thus got very large blocks of IPv4 addresses assigned to them, so in some cases they may be the last to deal with IPv4 exhaustion. (To be fair, though, many have given big blocks back for reassignment, doing what they can to have kept us from an exhaustion crisis before.)
Running an iPhone on IPv6 only far from new...
What Apple did with iOS9 is improve its address selection algorithm to prefer ipv6 in a majority of cases (if both the device and the server are dual stacked and unless v6 path latency is much greater than its v4 counterpart, v6 will be used).
In contrast, ios8 would prefer v4 over v6 when both endpoints were dual stacked.
Also, from what I've seen, iOS devices won't provision ipv6 addresses on their cellular interface unless their Carrier Profile says they should, so you might have encountered devices not getting ipv6 addresses even though they were connected to a dual stack network. Wifi always uses v6 if the network supports it.
What happens when you visit a ipv4 website, what IP address will site recognize?