It could be a poor bike fit. Also try changing positions on the bike frequently, especially on a road bike. There was an article in last month's bicycling magazine about neck pain. It recommended holding light weights and shrugging your shoulders to build strength.
Amanda
2011 Specialized Epic Comp 29er | Specialized Phenom | "Marie Laveau"
2007 Cannondale Synapse Carbon Road | Selle Italia Lady Gel Flow | "Miranda"
You don't have to be great to get started, but you do have to get started to be great. -Lee J. Colan