I suspect the reason they changed the date is because it interferes with the spring classics, primarily Leige-Baston-Leige and Fleche Wallone, which Lance would like to win and are good races for him. My understanding is that he was a bit worn out from the travel back to the US this year to be 100% for these races. Given that he rode the classics this year and would probably like to add wins to his palmares, I'd guess he decided to move the date of the US ride.