Was that a compliment?

I was riding in a group of about 300 bicyclists and had lost my boyfriend somewhere in the crowd. After looking around for sometime for him I decided I would most likely be spending the rest of the ride alone. Then, somewhere from behind me, I heard my name being yelled. My boyfriend quickly joined up with me. I asked him how he was able to locate me in the large crowd. “I looked around and then finally noticed your butt; I could spot your ass anywhere!” “Wow,” I said, “that’s sweet.” Really, why would someone say that?