Part of the reason we did not enable bumping in the background is we have received lots of feedback that people like the security aspect of having to open the a

Part of the reason we did not enable bumping in the background is we have received lots of feedback that people like the security aspect of having to open the app for an exchange to occur (picture girls at bars having guys hitting their phones into purses and pockets ;). The time required to bump on Android is (surprisingly) much less than on iPhone. Google doesn't seem to put the radio in as deep of a low power idle, so practically as soon as you open (or re-open) the app you can bump. iPhone takes a few seconds for the radio to warm up...