Good post. No, you're definitely not mansplaining... unless you repost this whole post on a woman's feminism post, I think.

In business and corporate situations particularly, women experience this a lot particularly when their expertise are considered less than their male counterparts. It can be subtle and constant vigilance is also needed to make sure we men don't go "oh, honey..." whenever a woman tries to speak up and make a contribution.

One way I personally have tried to address it is to make sure I support and not just rephrase a fellow colleague's explanation.