The Easter Freeze and pollen viability

Has anyone affected by the Easter Freeze checked pollen viability on roses that were blooming and heavily budded through the freeze?

In my garden, Canary Bird, R. primula, R. hugonis, Old Blush and Pacquerette all have blooms after the freeze although their petals show the rough time they had.

My freeze was temps down to 18F two nights running with twelve hours of below freezing temps.