2019 RDX SH-AWD Advanced.
We were passing a vehicle today. The car stalled and went into limp mode. 40mph max. Pulled over and turned it off. Waited a minute and restarted. It was ok. I too was in cruise control when this happened.

 

What is the question? There is no recall, only TSB and dealers will give you hard time before they do TSB

 

My mom had a 2019 RDX that ended up getting lemon'd out due intermittent limp mode. The culprit ended up being a hairline crack on one of the circuit boards in the ECU. An engineer from Acura Corporate ended up coming to the dealer to diagnose it.

 

Never experience Limp Mode in my 5 years of ownership nor 31K miles. May just be an issue with the 1st year of production of the Gen 3 RDX. I had my fair share of Mini's and Jeep's that served me up large portions of the 'Limp Mode" when the computer recognized a parameter outside the normal boundary. Never a fun experience nor an inexpensive fix.

 

It happened once to me in my 2019. Like you, I pulled over, turn off the engine, waited around 10 seconds and then restarted it. That happened a few years ago and has never happened since. Lucky? Hopefully.

 

Could have been a misfire(Bad gas possibly), a Computer or Trans shifting issue, too many variables to note.

As long as there is no CEL, you're good likely.

 

the tsb has updated part for turbo intercooler, which suggests during high humidity limp mode can happen.
I am sure there are other reasons for it also. It seems like this was more common at the beginning, but now not too many people complain.

the problem is that CEL code is automatically reset after you restart car, and dealers will most likely refuse to do anything. I dont think CEL is even stored in history, which is a horrible design