Yeah, that’s pretty much how heat pumps behave, especially early in the day when the air’s still cool. Mine used to drive me nuts at first, I’d check the temp every hour thinking something was wrong. Once I started running it overnight and threw on a solar cover, it made a huge difference.
Now, it might only drop a degree or two overnight, and by mid-morning it’s already back to temp. Heat pumps just work best when you let them maintain instead of “catch up.” If you shut it off completely, it’s like asking it to climb a hill from the bottom every morning.
So yeah, what you’re seeing is normal, just part of getting used to how they heat.