I just thought of this question when I did a push swallow and it does apply some force the kind that requires some consciousness. And is it okay to do this at a small degree?
Yes, provided you can isolate the tongue and not engage any other muscles, that is normal. Dr. Mike Mew talks about this learning process. In a previous topic about hard mewing, I quote him talking exactly about this.
Think of ideal mewing, as putting the tip of the tongue on the N spot and then applying suction and everything will fall in place, that's it. For people with CFD, there is an additional effort required like remembering to keep up the tip and apply suction consistently.
Hard mewing starts when, as it's name implies, you apply hard forces with your tongue against your teeth and palate for extended periods.
my story: http://www.aljabri.com/blog/my-story/