Glad you're feeling better, Crankin! Usually sudden body aches and fever do indicate flu. And the flu shot, as you know, only protects against whatever strains they think might be around that season, so you may have just gotten a different strain -- a relatively mild one, as influenza goes?
Hope leading the ride goes okay....
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow