Firmware Bug?

Hey Everyone,
I have had my iPhone 3GS for about a month now and I have just noticed something. Every now and then on the top left hand corner where it says your carrier and signal status. Sometimes my phone will say searching... 3G. Like it is stuck, it has signal, I can text and call but the phone is stuck saying "Searching...". Is this just a known bug with the iPhone? Also, if I put the phone in airplane mode and then turn it airplane mode back off it will fix the issue. Does anyone else experience anything like this?
Thanks.

 

Hey,
Yes I restored about 2 weeks ago. The phone wouldn't turn on it got stuck at the apple logo so I had to restore. Everything has been fine otherwise.