Running in my new cam shaft...

Started it up today to check ignition timing etc. checked the manifold vacuum with a gauge and before the new camshaft I had about 20Hg at idle (stock 252/252 2bbl cam), now it's only about 15-16Hg (Lunati description of the cam says about 19Hg), is it a normal drop of 4-5Hg whith the new 256/262 cam shaft?