Wow! I had the exact same experience as you --- also precipitated by the same "use pinkie sideways to support the bottom of the phone" usage. I stopped holding

Wow! I had the exact same experience as you --- also precipitated by the same "use pinkie sideways to support the bottom of the phone" usage. I stopped holding the phone that way, and it went away. The phone being big and heavy is quite insidious. Turns out that "you're holding it wrong" can really be a problem... not for the antenna/reception, but for our own hands.