Thanks for the many details. More questions may need to be asked to help you since a problem like this is tricky to diagnose at your home and even more difficult over the internet, so please bear with us.
A new problem on a new tank usually indicated something has changed recently, so let's start there...new water mains could affect pressure and introduce additional sediment to the tank as well as the natural build up from normal use.
Flushing your tank is a good first step. It will require you to shut down and then relight your gas water heater so become familiar with the process as it shows in your owner's manual and on the cover of the tank. You need to shut off the tank to avoid scalding and other actions that could harm your tank.
There are a few items that may be part of your plumbing system that we need to know about. I'll attach pictures to help with identification and you can let us know if they are there. If your water meter is in your home you might have a pressure regulator and/or a backflow device nearby. Since the tank is newer we also hope that there is a thermal expansion tank that was installed with the tank.
A question that will come up often on the forum is "what's your water pressure?"
Gauges are available at home improvement stores and hardware stores that screw onto a hose connection. (A valuable tool we would use at your home for any service call.) A gauge that goes from 0 to 200 psi should cover all possible pressures.
Since you said you're pretty handy, flushing the tank and checking the pressure shouldn't be too hard, but don't be afraid to ask for help if needed. You may get a variety of opinions as to how to solve the issue, but there could also be various reasons why it has started.
Alan sent a message to me last night about this problem and I didn't get it until this morning as I like my breaks from technology (this is my 'weekend'). That's why I referred you to this forum. If I'm not available there are a number of professionals that can help you. I'll be on my daughter's school field trip to the zoo tomorrow and orchestra recitals tonight, but I'll try to keep tabs on the thread.