Guys,
Our cars are notorious for developing a very slow leak on the passenger side of stock radiators, between the radiator core and the radiator end cap down low on that side.
It’s hard to see, and hard to diagnose, since it it’s a very slow leak and the leak mostly drips down onto the cross-member directly under the radiator, burns off, and never makes it to the garage floor.
Until I fixed that, my car had the same mysterious symptoms of a low coolant light every month or so, and overheating when coming off of a long freeway run and getting back into slow city street traffic!
When you are moving at highway speeds the air flow through the radiator is sufficient to keep the temps down. But, when you then slow to side road speeds and stop & go traffic, the system can't keep up.
Have your coolant system pressure checked to see if it has a slow leak. If it does, it's probably at the location I mentioned above, and may be the cause of the overheating you described.