Tire cup

I don't ride a trike but it has been my experence once a tire starts to cup on by bike it never gets any better.

There have been many posts on here about tire cupping. I believe most people wouldn't automatically give up on the tire once it happens. With only those few miles on it, I would ride it unless there is some shake or other indicator in the steering that there is a bigger issue. The propper pressure in the tire seems to be the primary key and is important for other reasons too, but you already stated you were aware of that.

On a trike most folks use a rear tire turned around backwards upon the front rim. This gives them a much stronger tire with higher payload ability and twice the tread depth for a longer life plus available in slightly wider width too.

IMO, under inflation is the number one killer of tires. I have had this happen to me, though I am usually very picky about tire pressures. I always use the pressure on the sidewall. Many people deliberately run low pressure "for a better ride" not realizing what it is doing to their tires and ultimately to their safety.

If the damage is pretty bad I would definitely replace the tire. If it is minor I would keep the tire properly inflated, use it, and see what happens. I am riding a bike right now with 3 plugs in the rear tire (a 750 cruiser) and the tire still has probably 10,000 miles left in it. I also have a bottle of Ride-On in it. I'm going to try to wear it out, or come as close as I can.