Lordhippos
Pokémon Master
It could also be a similar case to Inception and Paprika where many have assumed an anime's influence on Nolan's work. Planet of the Apes has also dealt with time dilation so the idea predates Gunbuster.
I think the entire time dilation thing is also based in scientific fact/theory about how time works differently under gravity, so all of the above probably got it from that as the origin.
Stuff based in real fact is cool and I appreciate how weird science stuff can translate into a compelling bit of entertainment in it's own right.