In the shipping-method selector, the radio button appears even if there is only one choice. It's a required field, so the customer must click it to proceed. In this situation, it's not obvious that the little circle is a radio button at all!
Do other people observe this? I don't think any of my customizations could be responsible. You'll observe this only if your shop settings have "Hide if one?" and "Select least expensive by default?" both off.
This isn't a functionality killer, only an annoyance, but we don't want to annoy our customers, right?
I'm running tip circa February 9.