I'm not a seasoned OP-er but I did notice when I first started my oil changed very quickly as well. I figured either a) I was very toxic or b) I had a lot of saliva in my mouth.
I have noticed as I continue to do it that it is taking and increasingly longer time for the oil to change. I started with 5-10 min and am now almost to the end of my second week and am up to 10-20 min. using Seaseme Oil.