Was I hallucinating?

Prior to going to see the Impressionism exhibition today, which I will tell you all about later, I ran up to the Kadoorie farm and back again as I had said I would. I took 1.5 hours AGAIN, which I am not proud to say. As I reached the long stretch of uphill towards the farm, as I was getting slower and slower and gasping louder and louder for breath, as Kasabian was blasting through my mp3 player, I heard this sound of a bunch of people shouting "Go! Go! Go!", clapping to a beat. I thought I was hearing wrong, perhaps some hidden background noise from the record that I never noticed before? But it kept on going as I climbed that hill. It definitely came from the farm. I took off one earphone and looked towards the direction of the sound, and it was definitely there. Well, either that or I was tripping on endorphins. When I eventually reached the top I turned round and come down again, feeling GREAT, I heard this loud clapping and cheering. I turned to look again but could not see anyone. All I could see were some cars parked inside the park.