You seem to be asking two different questions/making different statements here.
If you're chest is a weak part, then what you should be asking yourself is if the smith presses are helping bring that up.
If you're worried about getting stronger on free weight pressing movements, than focus on that.
Two different goals here. Nothing wrong with that, but you have to decide what you want from it.
That being said, if you're getting stronger on this, and are still also doing free weight movements, my guess is that you should also be progressing on those. However, if you have switched entirely over to machines and do no more free weight movements, you probably will have lost a bit simply due to not strengthening the stabilizer muscles necessary to lift free weights.