I'd say this sounds a lot like someone working the office blowing you off (not the athletic department as a whole or the entire Nebraska Football organization!). We all know BO and if someone asked him to sign something for a charity/community program/etc.. he would, of course, do it.
Someone just decided they couldn't be bothered to go rummage around for a ball or something, track down BO, get it signed, then find a box to put it in, throw in the ball with a message on department letterhead, tape up the box.. then get the UPS shipping label made and then off to shipping/receiving.
Next time.. I would suggest buying the football/whatever yourself, sending it to the athletic department with a return label.. so all they have to do is take the ball, get it signed, throw it back in the box and be done with it.
While I think that for things like charities and community organizations (especially in-state) it's not too unreasonable to ask for some autographs.. at least do them the courtesy of making it as easy as possible on them to do so.
So to sum up I see both sides here.. they (whoever it was) should not have led you to believe they were going to accommodate you and them blow you off.. and you probably could have done a bit more to make it easier for them to accommodate your request.
-tK (back from a long hiatus)