there are a number of small ~1/4 inch smooth bumps on the top of some of the...
there are a number of small ~1/4 inch smooth bumps on the top of some of the leaves on oak tree near the house. There is only one bump on leaves where bumps are present. Color is pale yellow and they are hard to the touch.
New Haven County Connecticut
From your description, it sounds like a leaf gall made by a gall midge, which is a kind of fly. The galls won't hurt the tree. In the fall, the gall will burst and the larva will emerge.