I've just bought (online) a new Castel lawnmower with a 5.5 hp Honda engine
and notice that the engine is bolted to the aluminium deck by three bolts.

The engine has four evenly spaced mounting holes but one of them does not
line up with a hole in the deck therefore the span between two of the
mounting bolts is approxiately 180°.

Should I be concerned about this??