There is a website that exists for the purpose of publicizing requests for bids. I think it would be easy enough to check if this particular contracting action was listed for bidding on the site. I wish I could remember what the site is.
There is also the possibility that the Air Force went for a sole source contract, if they felt that only SpaceX could offer the service they need.
With the different possibilities here, it is difficult to say whether ULA has a valid complaint or not.