Nah, I bet they got in, not on their own, but with the assistance of a third party "hacking" team. The last rumors I saw, of the solution they were going to employ, was basically copying the memory contents as they are, and then running their code-breaking routines on it, limitless without any timeouts.
They could have easily gotten into the phone already had the iPhone not threatened total destruction of data after 10 failed tries (it was unknown if that was enabled, but there is no way to tell), nor if they were hampered by the exponentially-increasing lockout time between attempts. Once you get past that limitation, it's child's play for any serious hacker.
But I imagine there was something a little more involved that simply copying the memory, because the encryption is two-factor: a hardware ID + passcode. Replicating the memory, through normal means, may normally render the data irrecoverable... but I'm not sure how that works.
If it was a simple copy of the data, I cannot believe it took so long for that solution to be proposed. I believe it was a third party company who handled that cracking routine. There may be some extra special sauce that was needed to be able to reverse-engineer the cryptography without the physical device. Perhaps it was a multi-step deal, where they ran hash-table attacks on the copied memory, and once they landed on the right passcode, then just input that onto the iPhone to unlock it. But I imagine it takes knowing the hardware ID that acts as one half of the crypto key. I'm not at all aware of what the iPhone uses so I'm really just making semi-educated guesses here.