After the game he went off on a pretty nice rant about the officiating, especially the non-fumble call on a key goal line stand.
I was watching a surprisingly good Browns/Bills game so I did not see this play live, but its clear that Texas fumbled/was stripped and Iowa State had a clear path to the end zone on the other end of the field. Instead Case McCoy scores the go-ahead touchdown on the next play.
As upsetting as the loss was, it was not the only thing that Rhoads was angry about. There was also the blatant cheap shot by Texas wide receiver Mike Davis that should have resulted in Davis being ejected.
So yeah, when his team ended up losing a close one under these circumstances it is understandable that he was kind of angry.
That was the juicy part of the post game press conference; if you want to see the full thing you can go here.
I can't say that I blame him for being so angry, and I commend him for not making it an expletive filled rant. Many coaches certainly would have filled it up with some choice words.