Tina is right, the depot of the higher dose can last 4-6 cycles, so he might still be feeling the effects of the .5 and .75U doses he got. Fortunately, the effect diminishes as the cycles go by so there'll be less depot effect tonight.
Your other option is to go to .25U, so just take a little off the dose. There are pictures of the 0.1U dose in the New to the Group Sticky. If you are worried about the night time, you can also leave lots of food for him to munch on if he goes lower.
They don't bounce when you reduce the dose, the bounce in reaction to either going lower than they are used to or doing a fast drop. Usually you reduce the dose as a result of a low numbers, so that's why you see a bounce then.