I just got the 4S today. In order to get my old apps/contacts/messages loaded I clicked "Restore from backup". Now I notice that in my SMS messages, some messages show the contact name but most do not. Upon researching I noticed the names that show correctly have their numbers formatted as "+1 (XXX)-XXX-XXXX". However I have entered in a new contact with the exact same phone number format and when I send a new text to them it shows their name. But as soon as they respond, it shows the number and appears under a new SMS thread (detached from the original one I sent). Any idea why the SMS app is not able to match the phone number of the incoming texts to the numbers in my contacts list?