I would charitably assume this to be the case. Plus a bit of machismo/bravado - it probably hurt a lot more than he was letting on. And the fact that he'd been keeping his powder dry in the shelter of the peloton for the whole stage, only showing his face in the final kilometre.
Anyway, it's not unheard of for previously "ordinary" riders* to come seemingly from nowhere and pull off wins like that, and you don't have to automatically assume the worst. Just look at Cobo and Froome in last year's Vuelta - what odds would you have got on them for the top two podium places before the race started? I know Cobo has hung around with a few shady characters in the past but that's not evidence of doping.
And don't forget that it's only in the last few years Wiggins has really started to shine - since he was about the same age as Westra is now, funnily enough.
Interestingly, watching the highlights again yesterday evening, earlier in the stage, the commentators picked out several riders in the top ten they thought might be a threat - they mentioned Spilak, Van Garderen, Jeannesson and Kiserlovski but were completely taken by surprise by Westra.
d.
