Megaman 2 OST ?

[Parable Dude]

While playing the game, I could help but notice that the level theme had a small portion of the 'Dr. Wily's Castle' theme from Megaman 2 (https://www.youtube.com/watch?v=WJRoRt155mA&t=42s , until ~0:53).
I don't know if the devs wanted to make a small reference (I couldn't find any credits), or if they have the rights to use parts of the megaman 2 OST at all.
I couldn't find any comments or discution about it, and I just wanted to point that out.