Question
I have a healthy blooming violet that has recently sent up 1 long thin stem.  It is not a leaf or a flower.  I have been asking around and only one other person said they ever had this and they never did find out what it was (they just cut it off)

Answer
Are there tiny leaves on this stem?

If so, this is called a "basket."  It is like a stolon from an episcia or a baby from  a spider plant.  Most AVs don't make these but it happens.  I've had two.

If this is what you have, like a tiny plantlet, allow it to grow then cut it off and pin it to the soil of a small container.  Put a plastic covering for a few weeks for humidity.  Treat as an adult plant afterwards.

Nancy