Washing Griddle before first use I recently purchased a cuisine art 5 in 1 griddle machine and cooked with it before noticing the instruction to wash it before the first time use.

Does this really make a difference? And is there any harm from not washing it the first time?
Whatever harm there was is done, so not much to do about it now, other than finally wash the thing before the next use.

New products often have either traces of materials from the manufacturing process, or a preservative coating for the time they spend between being made and being purchased; which is not generally something you'd want to consume. 

Whatever you cooked might have had some non-food grade oils, factory dust, or the like added by the time it was done cooking.