Mystery plant identified!

Have you ever had a seedling sprout in a pot or garden but it doesn't look like any weed that you recognise? 
So then you leave it to grow a bit longer just in case it's something good.

Well, I had that happen in a pot that had a gaura bush in. This is what it turned out to be:

A beautiful red snapdragon. :D So glad I didn't pull it out!