I'll try that next time (clicking the "x") - but the point is the iPhone has never behaved this way in the past and if that's the "new" way, then a dialog should pop up or something to notify us that backups are optional if indeed they now take orders of magnitude longer to complete than they used to.
BTW, I would post this to Apple as a bug, but that's a waste of time since they NEVER, EVER communicate the status of what you submit and everything I have posted in the past (e.g., cut & paste capability) has been blown off.