Gundy said he addressed the issue with players after Hubbard threatened to stop representing the university.
"In light of today's tweet with the T-shirt I was wearing, I've met with some players and realize it's a very sensitive issue with what's going on in today's society," Gundy said.
"We had a great meeting and (I was) made aware of some things that players feel like could make our organization or our culture even better than it is here at Oklahoma State. And I'm looking forward to making some changes and it starts at the top with me. And we've got good days ahead."
Hubbard also addressed the matter in a subsequent statement Tuesday morning:
University president Burns Hargis stated prior to the joint message that the school "will not tolerate insensitive behavior."