I'm the first to admit that I have no idea what he said. It did sound like he said a few words in Spanish. There has been discussions on quite a few tennis forums and twitter with regard to what he said. I'm only responding to suggestions that he could be swearing in Spanish. That would make no sense to me. No big deal.
I listened several times to what he said and I swear (no pun intended) that that first word ended in 'ol' or 'all', and so did a friend of mine who listened to it without being aware of the suggestion that it was the Spanish word 'cabron', so it could be anything really.
Anyway I feel sorry for Andy. Every little thing he says or does has to get dissected over and over - and it's possible he never intended what he said to be heard, although he did seem to say it quite loudly - but then, these court-side mikes are extremely sensitive.
I don't care if he occasionally swears in English when he's playing if it helps him get rid of frustration. At least he isn't in the habit of regularly smashing rackets up, because that's something I don't like to see - bad workmen blaming their tools springs to mind.