Definitely don't mention it again. She misunderstood the intent when she re-read it, the error was hers. As PP said you would just be reminding her about her own mistake if you were to bring it up again.

Move on and don't mention again, like all embarrassing moments. Otherwise you'll remind her of her mistake, and she won't love you for it.

If you've already explained what you meant and she heard and understood that explanation, I don't think you need to continue to discuss it.

My boss and I get along great, and text occasionally. She's in a different state. We have a weekly meeting with senior leaders, and often I text her in the meeting - like whose dialed in or commentary - generally short, informational.
This week our leadership asked about our confidence on a program schedule. We've been briefing issues for months. I texted her "low. Very low confidence"
After the call we talked and joked about the leaders asking that.
Today, she told me the text bothered her. She read it hours later and thought I meant she had low confidence. I explained no - the program! She remembered the meeting and laughed about taking it out of context.
I don't know if I should apologize again or never mention it or build her back up. Thoughts?