Morphing animation messes up San Francisco Display font

I really like how the colon character (:) is a little bit raised up and not touching the baseline in the San Francisco Display font introduced in WWDC 2015. Here is how it is supposed to look like:

However, once I changed the text of the label to something else with the .Fall animation, the colon dropped onto the baseline:

I believe that this is caused by the way you draw the text using Core Text. Can you fix it?