That is not my experience with DL. You can gain experience HP without ever orbiting.
You guys are talking about two different things.
You're talking about 20/20 hp to 25/25 hp-hit points gained from experience.
They're talking about 20/20 hp to 25/20 hp-hit points gained from repairing.
This isn't to say that you're not talking about repairing as well, but ships repair more hit points per turn while in orbit, so typically that's the only place where you'll see current hit points be more than max, although it can and does happen, less often, in open space.
I'm guessing it wasnt intentional, but that the devs didnt think it was a big enough bug to spend time addressing.
Sentient species taste better...
That's my understanding as well.