Possible health issue with new kits.

[KenoshaRabbits]

Hi there,
I am having an issue with 1 day old kits. There are 3 kits, born yesterday 5/18. When I went to check on them this morning, 2 of them had fur/hay stuck to their bottoms. It was mixed with what appears to be urine/feces making a sticky mess that took some effort to remove. While I've had many litters before, I've never come across this issue. Since I've been inactive in the forum I can't remember if this is a serious issue or not. Any advice would be appreciated.
Additional info, this is the 2.5 year old doe's 2nd litter. The first was a single rabbit that made it into adulthood.

 

[RabbitsOfTheCreek]

Just wipe it off

 

[KenoshaRabbits]

Just wipe it off

I know that part, getting them clean.

UPDATE
The runt of the 3 passed. Another one seems to be excreting sticky black stool. 3 times in the past few hours.

 

[KenoshaRabbits]

Update 2
All 3 died. Sad