I somehow doubt that digital clocks that run off of regulated DC power supplies are going to be affected by a slight change in the grid frequency, or even a huge change in grid frequency.

The only clocks that would be affected are old, 100% analog AC wall clocks, and I honestly cannot remember the last time I saw one in use. Your VCR, DVD player, coffee maker, stove, alarm clock, electric toothbrush and anything else with a digital clock on it should not be affected.