yeah, it must've installed the latest ofw at the time. the automatic update feature has several options, some of which are for psn+ only, such as automatically syncing trophies and saves. it's like windows where you have to set non active hours for it to turn on then sync or download the latest updates (in two hour increments). I'm not 100% sure if it installs automatically, but it will download during those non peak hours. that's also when it downloads or continues downloading content from the ps store, because iirc, it won't download while in game. I guess there's not enough memory available or something. anyway, downloading the latest update doesn't need psn+. while it may not install automatically, it may force you to, if an update is downloaded, unless you format the hdd.