Hi, You used one of the formatting tools when you entered your question. I've done that too, but caught it and gone back in with editing to fix it. I think that you likely clicked on one of the icons directly to the right of the bulleted list icon.
Click edit your post and then use the preview box below to help you get it back to normal size. They we won't feel like you're yelling at us. :)
The first one adds a heading
The second one separates text.
But sometime when I'm formatting something, I click on the wrong one and getting a heading instead of the line.
What may have happened is that you used the second one, but didn't like the spacing and so took out the space between the text and the bottom dashed line.
When you do that, the text changes to the heading font.
And note that you lose the dashed line in the viewable text, but not in your original entry. Why this happens is a mystery for the webmaster.
Pam
[Editor's note: Fixed it for you, this time. Laura]