I should have known better and remembered that it can take a day or two for hard frost damage to show up.
It seems that was heavy damage on rapidly growing perennial and bulbs. It wasn't garden wide, just in certain spots.
The roses were the hardest hit, they had several inches of growth that is now wilted and crispy looking. The bleeding heart completely collapsed and my hydrangea is completely brown. The biggest surprise was that some of my daylilies and Asiatic lillies have MAJOR damage. I'll know in a few days if they have chance this year.
On a brighter note, I noticed tiny roots on the pepper seeds from Granny that I started pre-sprouting on Sunday!