Gerbil Has Persistent Bleeding Nose
My gerbil always seems to have a little blood on his nose, and its sometimes crusty too. I am convinced this is not due to his teeth being overgrown.
It is always worth a visit to your vet when self-diagnosis is not possible, especially because the gerbil may have other symptoms that you may not be aware of or know to look for. You are right to first consider the teeth. In extreme cases, when gerbils do not have an outlet for gnawing, the teeth can grow so large that they cause a bleeding nose. However, you seemed to have checked this, and its generally safe to assume that if the gerbil is eating normally the teeth could not have grown to this extent.
Gerbils are such industrious bulldozers that they are also prone to dermatitis of the nose, which would normally result in slight bleeding and dryness if left unchecked. This is nothing to worry about, and you will find if you give your gerbil plenty of soft bedding, such as tissue paper, the little blood there is will be absorbed by the bedding, and you will stop noticing it.
However, if this persists after providing softer bedding, please consult your vet.