Here is a better photo of the branch in question.

Yes but I would not worry about it until mid-to-late May anyways. Good close up picture though... I have such a hard time doing those close-ups that I just about have given up hope (having an old camera does not help)!!!

Those are live buds. A hard frost may or may not kill these, but give them time. Lots of hydrangea buds come with blackish casings from which green leaves begin to emerge. H. serrata buds are also much smaller than those on macs, so they can easily be mistaken for dead.

For example, my Grayswood serrata's buds looked shriveled and almost non-existant, but low and behold green leaves are coming from all of them, and the plant is on the north side of my house.

they are calling for a freeze warning tonight...should I protect this hydrangea, if so how?