Anyone noticed any changes regarding signal strength or reception for better or worse with iOS4? When I upgraded to OS3.1 and I went somewhere without coverage,

Anyone noticed any changes regarding signal strength or reception for better or worse with iOS4? When I upgraded to OS3.1 and I went somewhere without coverage, my 3GS sometimes refused to come back from "No Service" until I either did a cold reboot or switched in and out of Airplane Mode. Then it would work fine again, so I suspect it was a software issue and not the network (Vodafone in Perth, Australia). Has this happened to anyone else here and have you noticed any change in iOS4?