I tried to look the hawk up in my Stokes bird book.
Looks like it could be either a juvenile Sharp Shinned or Cooper's Hawk, both are quite similar.
I think the squirrel was in little danger since he was in his element where as the hawk wasn't. Now put that squirrel out in the open with the hawk in the air, and the result could be much different!
Smart hawk knew when to retreat.
Gabby