My horn blows by itself in the mornings when it is cold, whats the problem?

It started off that it seemed the horn was getting stuck at random times but all this week when I start my car in the mornings it is constantly blowing. I thought it could had been the relay so I changed it and put it in yesterday evening. Drove home with no problem, even honked a few times and it didnt stick. So this morning I get up to start my car and it is still doing it, so apparently it is not the relay. Any ideas?