I've had the Maxx since October, activated the SIM card then, everything's been peachy since. Today out of nowhere there's suddenly a notice on the phone "SIM Card Activated, your new phone number is (same as current phone number) ...". I went online with Verizon to see if anything had changed with my account. They made me pick a "security image" and question but everything seems normal. I guess I'll just ignore it, but it's weird. The phone hadn't been shaken or subjected to anything which could conceivably dislodge the SIM card.
I've gotten the same message after coming back up the stairs from the basement at my job which has no service. I've also gotten a notification saying that my google account is deactivated and to re-enter my password. I have no idea what "Sim card activated means".
I just did a factory reset last week and you get that message about the SIM when you first turn on the phone and start the setup process. I think Masheen could be right - you were out of service and came back or something. Having to reenter Google account passwords happened to me once before, in February, when I was in a restaurant with no service for a couple of hours, but I didn't get the SIM message.
Maybe there was some sort of service that crashed and the phone started the initial setup again? Or an internal database that stores this info about your account was corrupted and recreated, causing the phone to go through checking the SIM again? If you start seeing other weird things happening, it may be time to factory reset. That said, that's obviously the last step. If that was my phone I think the first thing I'd do is restart it.
Let me throw my hat into the ring and add this has all happened to me as well. I truck between California and the Midwest every week and there are areas I travel through that if I lose connection long enough I will get the 'Google account deactivated / re-enter password' and 'Motorola ID services has stopped' messages. Normally, once I'm back in coverage, the messages resolve themselves and go away.
About a week ago was the first time they didn't. It was also the first time the 'Sim card activation' message was with them. When I got back in coverage and I saw the messages still there, I tried a reboot. When that didn't work, I pulled over, entered my Google password, the messages disappeared, and all was right with the world once again!