Just recently my 3G has been staying on (and active) while wifi is connected. I know the wifi is good - using the browser I can check my IP to be that of my home internets... I've tried killing all running apps to see if something had the 3G connection stuck on, and even doing a cold boot right into wifi. Something is forcing the use of 3G and I don't know what it is. Any ideas?
I see that sometimes too. What i do is turn off the mobile data for a bit and then turn it back on and it usually goes away. There are a few native Verizon apps that require 3g only service to check to see if they're updates available. I hope this helps a little. I forgot which background apps require 3g, or I'd list them for you.