span tag and line-height style randomly inserted

Since upgrading to 3.8.1 I’ve noticed that

<span style=”line-height: 1.5em;”> and </span>

are randomly inserted into my posts. I’ve only noticed this with the visual editor. Normally I use the text editor and don’t have a problem, so maybe this was a feature in earlier versions too?

As yet I’ve been unable to isolate the steps that lead up to the tag being inserted. I only notice it because the preview shows the text highlighted.

Obviously it’s not a major bug because I can delete it, and even when it is not deleted it is only a slight annoyance.