There are many occasions that I dont know why people use past tense instead of present tense. As for example, arround three years ago when the then 6 years old Connie Talbot sang Over The Rainbow at The Britain's Got Talent Show, Simon said, "I thought you were fantastic!" The other judge said, " I thought you've sung that beautifully."
They gave those comments right after that girl had sung the song. Why didn't they use 'think' instead of 'thought'?
By the way, am I allowed to post that link here? (It is a four minutes youTube link)