Flexwatt and newspaper: not enough heat getting through?

I have a rack setup with a herpstat, sterilite tubs, 4" flexwatt, and newspaper substrate(I've tried everything else, the veterans around here were right, newspaper is just the easiest). And I have the probe directly on the flexwatt as I've been suggested to by people around here.

The temp on the surface of the newspaper on the hot end of only reaches 89 or so (I have the herpstat set to 95.5 or so). I know the snakes can bury under the paper to get warmer but a lot don't seem to do that right after eating. It is probably not a big deal but I just want to make sure they can get hot enough to digest well.

What made me post this is that I just fed everyone last night and some of my snakes were only laying on top if the paper and I've never seen them
under the paper to where it's warmer. I guess I'm just worried they are too dumb to realize where to go to get the heat.

But I may just be worrying too much. They all seem
fine so maybe I shouldn't worry.

The difference in temp between the bottom of the tub and on top of the flexwatt should not be very different at all. Newspaper is not very thick :P . Just make sure right on the plastic it is between 92-94 and I am sure your snakes will get plenty of heat.