D13b1 Rocker arm play?

Hey there, this is my first post on this forum just trying to get some info, ive just been adjusting the tappets on my d13b1, (im sick of it soundign like a tractor) though whilst adjusting i noticed the rocker arms themselves have a little play (probabaly about a mm or so) now this doesnt seem right to me, i would think that if im trying to get the valve clearance exactly right then the rocker arms shouldnt be moving as im doing it, can anyone give me any insight as to wether this is bad ju-ju as i have never encounterd anything like this before.

In what way do they have play? Side to side??