We don't have evidence, this was sparked by her account tweeting toward Elon speaking about "your mom" in third person and saying effectively that she met herself in 1966.

However, since the story didn't even make sense accounting for the third party tone, it's more likely she meant to say "your grandmother" referring to her mother-in-law. Though they deleted the post rather than explaining/correcting, which is weird.

However it's also plausible because we know he has done sock puppeting, including his toddler son. I feel like sometimes she had weirdly conveniently timed and worded posts to reinforce some point Musk said.