Hi and welcome to Pet Talk!
I have had two gerbils, so I'm pretty experienced.
My current gerbil is Oreo Sue(as you can see her picture on my sig)...her nose has also often been bloody, there is nothing to worry about.
I have often read that gerbils with bloody nose's can mean two things.
1-They might be allergic to their beding.(what kind of bedding do you use?)
2-Gerbils are curious animals and like to dig and tunnel...sometimes moving bedding with their nose makes it bleed, but it goes away quickly.
I hope this helps,
Alyssa