I don't think that a momentary drop to 13V means that a smart charging system alt has a problem. You can have the charging system tested free at a parts store, however I'm not sure how valid the results from those testing tools are for all of the different smart charging systems in use these days. One DIY load test that I like and have used over the years would be an easy thing for you to do, and might give you another perspective on the health of your charging system.
To run the test, you'll either need a helper, or else multimeter leads that are long enough to be able to read the meter from the driver seat while it's connected to the battery. The test starts with a fully warmed up vehicle - a good time would be after returning home from a 1/2hr+ drive. I've always done this test with the engine at idle, never touching the gas pedal. Some flavors of the test call for a constant, higher RPM (1500, ...). However, that would require blocking the gas pedal into a fixed position, because no one can keep their foot steady enough on the pedal to produce a continuous, non-variable RPM for the length of time it takes to do this test. I don't believe it makes a big difference what RPM is used, provided it's constant, but that's JMO.
You start the test by turning off everything electrical in the vehicle that's switchable, and checking the running battery voltage. You can record voltage readings, or not as you choose. Then you start turning the electricals on, one at a time, and monitor the meter readings the entire time you're doing this. On my vehicles, there is typically a very brief voltage drop followed by a quick bounce back for some of the higher draw electricals. If anything produces a voltage drop that doesn't bounce back, I'd wait for at least 30 seconds to see if it does eventually bounce back to at least the starting voltage reading.
You don't shut anything back off during the test, so by the end of it everything that can be switched on will be running concurrently, including the blower on high with A/C on (or whatever 'max' setting is available for auto climate controls). Save turning the wipers (on max) for last because you'll need to keep the windshield wet to avoid damaging the wiper system, and will want to use as little water as possible with the hood open. If something didn't go right or doesn't seem to make sense, just start over and run the test again from the beginning.
Even though I wrote a lot, it's really an easy test to do, and it may very well make you feel more comfortable about the condition of your charging system. However, if by chance your vehicle's charging system begins to struggle, or shows unexpectedly low voltage (which doesn't come back up) as the testing moves along, then that would be an indication that there may very well be an issue with it.