G,
Remember even the best of us in a new situation can do silly stuff because of the pressure of a situation.
Although a SEP club check is a relatively relaxed affair as checks in flying are concerned, there still is the element of flying something new with some one new.
As an instructor it is very easy to demonstrate stuff perfectly when you are controlling the pace of the lesson. So for an instructor switching back to being the student there is still the potential to perform less than 100%.
It depends if he/she recognised at the time if that was incorrect action.
I know during sim sessions on the heavier stuff, I have often found myself often making the same mistakes that my students make on the light stuff. As a moderate houred GA instructor these are mistakes I shouldn't make but sometimes the pressure of the situation can make you do stuff that makes you look as though you have never flown before.