Should I breed her?

I was planning on supervising anyway.

Would the nose rub really be that obvious to another snake? She doesn't act strangely usually. Lately she hasn't been rubbing at all.

To answer that I would need to know how a snake thinks. Snakes are predators by nature, therefore making them more aggressive. If it feels uncomfortable being in the same enclosure (1 snake 1 cage -- less stress on the snake), it could be more opt to attack. Putting them together even to mate probably causes a stress.

I will say that I know jack squat about snake breeding, Adam or someone like him would probably be better to answer these questions. He has a lot more first hand knowledge of snakes and thier breeding behavior. I could be completely wrong on this. I am just recalling how animals in the wild, or captivity for that reason seem to weed out others they suspect as being inferior.

I know it's fairly common - for the male snakes at least - to go on nose rubbing sprees in mating season because of their desire to find a mate. That doesn't seem to cause any harm to them when they are breeding though.