2017 RAV 4 LE engine tick

[harkauto]

I pulled into the garage with my 2017 Toyota RAV4 and I got out and left the engine running so I could get out and move something and when I exited the running car much to my shock I hear this fairly audible tick..tick..tick..tick..ticking noise coming from the engine compartment. I popped the hood and found the noise was definitely coming from the engine compartment, but could not see any obvious causes of the noise.
I'm just wondering if any one else has had any experience with a ticking sound coming from the engine on their 2017 RAV4. The car has 30M miles on it and the oil has been changed religiously. The strange thing is, I took the RAV out later that evening and when I returned home I checked again and the car was not making the ticking sound at all.
Any ideas what it could be that is causing this tick...tick...tick. I'm reluctant to drive it for fear of damaging something.

[Stealthee]

Probably the slightest exhaust leak. When things got hot enough they swelled and stopped it. It could also be simply the exhaust getting hot and expanding. Metal makes funny noise when the temps change. The roof on the building where I work creaks and pops when the sun comes out

[harkauto]

Originally Posted by Stealthee

Probably the slightest exhaust leak. When things got hot enough they swelled and stopped it. It could also be simply the exhaust getting hot and expanding. Metal makes funny noise when the temps change. The roof on the building where I work creaks and pops when the sun comes out

Update:
In the two months now that I have had the 2017 Rav I have now experienced this engine tick three times. I understand the theory of hot expanding metal and how it can make noises, however, I have ruled out the expanding metal theory because the tick, tick, tick, tick speeds up when I accelerate the engine and then slows when I decelerate.
This ticking noise is not constant and for some reason it comes and goes, but my 1999 Toyota Camry which had 230,000 miles on it ran as smooth as a sewing machine and did not tick at all.
An engine tick on a car with only 33,000 miles on it makes me very nervous.
I have all of the service receipts from the dealership and this Rav 4 has been maintained religiously with proper oil changes and such.
In all my years of car ownership I have always understood that and engine with a tick, tick, tick is NOT a good sign. This makes me very reluctant to take off on a 5000 mile vacation road trip with this engine.
Toyota's response is "Hey"..you do have the extended drivetrain warranty on the car, so don't worry about it". This is easy for them to say, but if my wife and I find ourselves stuck in Tim-Buck-Too New Mexico with a blown engine and 200 mile from the nearest Toyota dealer my extended drivetrain warranty won't be much comfort.
Toyota claims they can't be of much help unless they can hear the tick, tick, tick for themselves. Problem is, the noise is so unpredictable and infrequent that it is difficult to have the car making the sound at exactly the same time I would have it at the dealership.
Something has to be going on within that engine in order for the tick, tick, tick to speed up or slow down with the speed of the engine.
I just wonder if any other RAV4 owners have experienced this.