IMO she told Lacasse but not as a joke, so later she had to repeat it as if she was only joking, and she did to the repair man
IMO when she'd told Lacasse it was a risky mistake, not a joke ( Lacasse also emphasised it wasn't) , it was a confidence, possibly as have said before, the woman who "drank her dinner" was a little inebriated at the end of the date when she told him. ( Also Jeff had started to hate Dan too, it's there in his interviews. He was an easy person to speak the unspeakable to)
I think she reflected on that risky mistake in the days thereafter and she worried.
Also JL testimony : " WA has a habit of blurting out things which are not in her best interest"( or wtte)
eta quote for that point about why it might be easy, drunk to say that to Jeff:
JL interview:
“She meant it, dead serious,” Lacasse continued.
“I would joke around, saying I’d like to kill Danny Markel. ... That is different. She said it in a dead serious, chilling, uncomfortable way. ... In the moment, my stomach flipped. I was like, ‘Whoa.’”
Dan Markel was killed on the morning of July 18, 2014, at his home.
abcnews.go.com