For the last day or so, my phone, which I've only had a couple weeks, hasn't been syncing with Gmail automatically. I've restarted the phone twice to no avail. It will sync if I trigger it.
I also noticed that my phone slipped out of 4G into 3G a day or two ago. After the first reboot, it went back into 4G, but the 4G indicator and bars are grey instead of blue, as is my WiFi indicator. My Twitter app isn't having any issues connecting and updating.