Thge panel in 'frame and panel' construction is designed to float to allow for wood movement. It can be tight in the direction of the grain since movement there is very small, but across the grain in needs to be free to change as the moisture content varies.
If it really bother you the panels can be carefully fastened in the center of 2 opposite sides to prevent the rattle.

aS a cabinet maker, i feel bad for ya. Your guy, should have put space balls inside tha rails / stiles, they would have allowed for the movement of the wood, yet provided a solid feel. If there is a gap large enough on the inside of the door panel, try sticking a 8 penny or smaller nail to wedge it tight.

Since you've got simple flat panels I'm guessing they're likely to be plywood or MDF, in which case they don't really need room to move at all.

Someone just asked a similar question over on the kitchens forum, and got some useful suggestions involving creative use of caulk...

Here is a link that might be useful: parallel thread

"likely to be plywood or MDF, in which case they don't really need room to move at all."

Plywood and MDF still move, just a lot less (MDF moves more than ply).

Correction : MDF does not move, not when sized correctly. It is not like ply which is still technicly wood. I have used MDF in wooden frames (space balls) in cabinet doors for the last 7 years. NO callbacks, no complaints.

My ninth grade biology teacher once confessed, on behalf of the whole teaching profession, that teachers in earlier grades "lie" to their students, because concepts are initially taught in greatly oversimplified forms. I guess I'm guilty too.

Engineered wood products do move. I read one study that placed pieces of wood, particle board and MDF in a box maintained at a dripping 100% humidity until they'd all swollen to their maximum dimensions. The plywood fared the worst, i.e. swelled the most, probably because it's less thoroughly permeated with glue. On the other hand, in less abusive environments like my non air-conditioned shop, scraps of plywood that sit around seem to fare better, probably because solid wood (or veneers) are better at recovering their original dimensions when the humidity drops whereas MDF and (even more so) PB swell at the edges and stay swollen permanently.

When I said that engineered panels don't move, I meant that they don't move enough to require expansion and contraction space in a frame. Whereas solid wood panels "can be tight in the direction of the grain," engineered panels can be similarly tight in both directions; there is no "across the grain" where it "needs to be free to change as the moisture content varies." However, getting an absolutely tight fit would require the panel width and rail lengths match with a level of precision that is fussier than need be, so building in a bit of slop is expedient. The relevant point for the OP is that, I suspect, they took that expedient sloppiness a bit far.

"Correction : MDF does not move, not when sized correctly. It is not like ply which is still technicly wood. I have used MDF in wooden frames (space balls) in cabinet doors for the last 7 years. NO callbacks, no complaints."

MDF sure does nove.
If it did not you could safely frame with no clearance and no space balls. Try it wome time and let me now how long before a corner joint blows.
MDF panels stil require some room for movement. It is a lot less than solid wood, but move it does.
jon1270 knows the drill.

Okay, I succumbed to my desire to put some numbers on the debate. I found a nicely written PDF file from the Composite Panel Association, linked below. They illustrate movement with examples of how panels react to a change from 40% to 85% relative humidity. According to their summary mdf swells, in both length and width, about a quarter of one percent. For a 10-inch panel, that works out to 25 thousandths, which is not a whole lot but is more than I would have thought. My apologies for overstating the case. Apologies to the OP as well, for getting so insider-baseball about this.

Here is a link that might be useful: Dimensional Stability pdf