Saw this today when I was going out of my work at JcPenney and I hardly get reception and then turned off airplane mode and this came up followed by the "E" and the "3G."
I get that all of the time when I'm too far out of my wifi range as I live in a village. If I go on a walk around that village i get that. Most of the time though I'm either within range of my WiFi or in the local town which gets 3G and them places with rubbish signal are actually quite rare :L.