Blood in saliva. Blood in saliva. thnx!

Hello sir. I have a concirn. I never smoked ciggrates. Never had alcohol in my life. I use to have hukkah ( flavored sheesha) for a while. Now I have even stopped that.. From few days I have noticed. That when I wake up in the morning. Of afternoon.  The saliva that I spit out is a bit brownish in colour. Other wise entire day its absolutely clear. It is just when I am lying down to my bed for hours. My spit when I spit out is a bit brownish or sometimes reddish blood types. I had gingivitis 1and half year back. I got it cleaned. Again tartar and plaque is build up. Sometimes i can see blood tinged in tooth also. My concern is i hope it is not cancer.... Im very much tenced I'm 38 years old. I have No problems or other symptoms No chest pain No cough at all No shortness of breathing No weight loss No appetite loss. Plz suggest. I hope it is not related to cancer because i get tenced wen i c brown saliva or a bit of blood in saliva. thnx