2005 Neon SXT - Is this just the nature of the beast?

My question is about a 2005 Dodge Neon SXT, with 2.0 SOHC, automatic trans. Purchased December '05 with 27 miles on the clock. Currently it has about 3,700 miles. Maintenance of course done on schedule at the
local 5-star dealer.
In particular, I'm wondering about the engine.
First, I've heard that piston slap on start-up is normal on the 2.0 SOHC's, and DCX's official line is that it doesn't affect engine life. But is there a point where it's NOT so normal, i.e. when it seems to have gotten a little louder over time? I've noticed the piston slap since day one and tried to put it out of my head, but it has gotten noticeably louder since the first oil change. It's not deafening, but at the same time it's not a noise you expect to hear out of a relatively new car.
Depending on the day, it can take anywhere from 30-60 seconds for the noise to subside. Anyone know if this, or the mild increase in noise, should be of concern?
Second is a behavior I noticed a little bit later than day one, say at about 1,000 or so miles. I'm noticing that once the engine is warmed up and running for a while, the engine will alternate regularly and frequently between a smoother and slightly rougher idle, particularly when in drive and at a full stop (i.e. waiting at intersections and traffic lights). For about a half a second the engine will idle smooth, then have a slightly rougher idle for another half-second, then alternate back to smooth, and will keep going back and forth like this. Passengers don't notice it unless I point it out to them, but *I* can feel it, having my foot on the brake and hands on the wheel where I'm feeling the vibration level change back and forth. It's acting almost like there's some kind of additional load being applied and then removed every half-second.
The RPM indicator stays rock-steady however, at about 950RPM or so. As soon as I apply the gas and get underway, performance is smooth and uniform until the next time I have to come to a full stop.
Is this, like the piston slap, "normal?" I can put up with both if there's a certainty that there's nothing wrong. I certainly have no other complaints at all.
On the other hand, if there's a problem, I'd like to get it fixed now rather than wait for the latter half of the 7/70 powertain warranty for these issues to be more... obvious.
Thanks for any input!
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