Amazing that there would be a drop of blood coming out of bottom of nest and not a significant puddle inside of it.
I would be too, that more that I've seen from a comb or foot injury.
I guess just keep a close eye on things....hopefully it was a one-two off.
I'm no expert but .....
Dripping from the nesting box...or dripping into the nest from her as she was laying?
Was the blood coming from her hind end....was there blood on the egg?
'Dripping' as in multiple drips..2-8-20 drips?
Did you check out her vent after she laid?
That's quite a bit of...