Ah, that would be it, yes.
See, Banktoad changes form everytime you reach a certain threshold of Star Bits. I want to get him 9999 to see what his ULTIMATE FORM is. When I reach that point, then I will go back and feed all the Hungry Lumas all in one fell swoop.
I have this fear of finishing the game too soon, so I've been saving a lot of stuff like that to do later. Like, many of the Second Stars in each world.
Man, but some of those Purple Coin challenges are diabolical, aren't they? In Clock Ruins, "The Adventure of the Purple Coins" had me holding my breath. Collecting purple coins on giant rotating clock hands? Whoooeee.
The one in the giant tree trunk was cool, though. I love anything that takes me several tries.

Naturally now that I've beaten Bowser I use Luigi a lot. Mario and Peachie need their time alone together. I'd hate to disturb him.
"What? There's an S-World? @#$% ME! Mama mia, all right, I'm coming... Well, Princess, I gotta go, there's still more game. I need my overalls back."