[mcfrl]

In use the single tap was too easy to fire when you inked near it, and got in the way of the pull a little.

Tip: Shake opens the action sheet too. You might find that nicer.

[gdubs]

Shake is often used for undo, which may be a nice feature in keeping with the minimal feel -- you could even have an extra long shake prompt the user to see if they would like to clear all.