TXPO:
From what I've seen since my 40C grew a dead trigger some time back, a new gun should NOT do this unless a DCAEK (or at least the sear & spring modification) was installed. My bet is still dirt/crud around the sear, or spring/trigger bar issues.
It also appears that S&W is "slipstreaming" the upgrade where you're not automatically getting the MA-compliant sear block. Which means that a new gun could still get the older block.
(The MA-compliant - Massachusetts-compliant - sear block uses a larger sear spring and sear return plunger. With a slightly lighter spring, the "feel" is just a bit heavier than the basic design. Everybody else
was getting the basic version - the one with the microscopic spring and plunger. Somewhere along the line - perhaps when these problems started cropping up - S&W apparently decided to use up the older sear blocks and start shipping only the MA-compliant version eventually. The only difference being a MA-compliant spring for MA....)
At this point, the aftermarket suppliers (Brownells and Midway, AFAIK) seem to have the older blocks, but who knows. I don't think they know.... (And it's impossible to tell without taking the sear out of the block....)
It's said that S&W won't upgrade a block unless you have a problem - and, I suppose, they can detect it.... Apex will upgrade a block and provide the new plunger and spring for their customers for something under $50 (you can ship your old block any old way - it's not a "firearm" - but something traceable may be a better idea). Non-customers are expected to pay a bit more, but it's "no questions asked"....
Hopefully S&W will fix things, and upgrade the sear block, too

....
BTW, Apex's DCAEK kit now includes a replacement sear spring for both blocks - saves paperwork and hassle.
You CAN upgrade your own sear block, but nobody seems to have plungers. I think Apex is making their own. Requires a good mill and a cutter that can handle the relatively hard block material. Apex told me that they're burning up cutters pretty quickly. The "odd" part of the job is that the side of the cutter has to take a divot out of the side of the "slot" in the block where the plunger & spring live. Otherwise any old drill press....
Can't wait to hear!
Regards,