Could be the saline solution. Some people just get nose bleeds. I've been getting them, mostly in my left nostril, since high school off and on. It's worse in the winter when it's dry outside. If you have allergies or other reasons for your nose to be often congested, blowing it can irritate dry and perhaps thin skin. Why some get this and others don't is unknown, but it could depend on several different factors. If you use something in there often that is likely to dry the skin out, bleeding will be more likely. Don't put any petroleum produces in there. I was advised by a school nurse in high school to put Vaseline in there to keep it supple, but of course that product does just the opposite. Try not to blow too often or too hard and know that the more product you use to control the congestion the more you're also going to reduce the mucous that is useful to keep the tissue from being brittle. It is what it is. Peace.