Hello Neoinfojunction. You are correct. The minimum payout for any qualified subscription is $1.50. You'll notice if you look in your report that the $1.35 is actually a payout you are getting for a rejected offer. Why are you getting paid if the offer was rejected? I will explain.
The earnings that you see for a rejected offer were generated not for the main offer that the user subscribed for, but for an offer that was located in the co-registration spot on the qualification form. As you may have noticed, at the end of some qualification forms for certain offers you see additional magazines, downloads, etc. being listed. If a visitor to your site, fills out a qualification form and selects any of the additional offers listed at the bottom of the form, you will earn a share of the revenue generated from those actions. So, even if the user doesn't qualify for the main offer, there is still a chance for you to generate earnings from subsequent offers.
Below is an example of what these offers could look like:
This explains the extra earnings.