I've noticed a really peculiar bug on my 4S. When I get SMSs and don't check them, when I look at the phone on the lockscreen and notification centre they are displayed as their number (like 83 777 for Twitter) instead of the contact name. It randomly shows some contact names and some numbers, even though they are all contacts. They all show fine in the messaging app itself, it's just strange how they randomly decide to not show the names right. Anyone else getting this?