Spokesperson Annie Skinner stated today that Horner had updated his whereabouts properly, but the updated information was not relayed to the Spanish doping control officer.
"In response to public statements from Team RadioShack today concerning Chris Horner, USADA can confirm that we were coordinating an out-of-competition test with the Agencia Española de Protección de la Salud en el Deporte (AEA) while Mr. Horner was in Spain. Mr. Horner properly updated his whereabouts information in advance of the test attempt, but given that the information was received in the U.S., the AEA doping control officer on the ground in Spain did not receive the updated information prior to arriving at the hotel.
"This is not considered a missed test and neither anti-doping organization provided information to the media regarding this situation. USADA has a strong collaborative relationship with AEA and thanks them for our on-going partnership in protecting the integrity of sport and the rights of clean athletes."
The American came under scrutiny as he closed in on becoming the oldest rider to win a Grand Tour by several years, with many questioning how a rider of that age could best champions a decade or more younger.
Less than 24 hours after Horner emerged victorious from the Spanish tour, the media in that country published reports of Horner missing a doping control.
The RadioShack team was quick to respond that the fault was that of the testers, and not Horner, going so far as to issue a screen grab of the rider's whereabouts update to USADA.
Horner is set to compete with the US national team at the UCI road world championships in Florence, Italy next.