online and Ea origin

Yesterday, I was playing a single player campaign, then out of nowhere there had been an error ( I didnt remember what type of error it was, but it was definitely an error) and with that, I was forced to be out of the single player and put me in the main menu. But then, before I tried to to go back for the single player, there appeared something about this EA origin, making me input a username for registration, unhesistantly I input my username. This time, I did not decide to go back playing to single player campaign but to Online. I know that I dont have any Playstation Plus yet on my account and I also know without a subscription to the PS plus I cannot have any access to the online features, but at that instant I was given an access to multiplayer. With this I managed to play the multiplayer for, I think, maybe 20 minutes. After that, I was disconnected. So I tried to go online again, but this time, a prompt always appears that I should have a PS plus to gain access with this online features.

My question was, how did I managed to gain the multiplayer without PS plus (at that moment)? I was left curious with this incident. I just also thought that maybe it had something to do with the EA origin account. Or maybe I was a given a 20 minute trial of multiplayer or something.

Hope you can help me. Thanks!