A paper describing the first evidence of top pair production in association with a energetic photon has just
appeared on the Cornell Arxiv. This search has been performed by the CDF collaboration in a sample of 6 inverse femtobarns of proton-antiproton collisions.
There is nothing strange or particular about the fact that any hard production process at a hadron collider can produce, in addition with a massive state such as a top pair, additional energetic photons. That is because any charged particle involved in the process will have a small but finite chance of radiating electromagnetic energy, with a strength governed by our good-old fine-structure constant.