Indeed... just because something is dukkha vedanā (unpleasant feeling) for one person doesn't mean it's universally so for each and every sentient being.
Whether something is pleasant, unpleasant or neutral is actually an attribution made by the individual, rather than some absolute and objective quality - this is something that can be seen by oneself in meditation.
Even outside of meditation, personal taste is evident. For example, the sound of Bob Dylan is dukkha vedanā (unpleasant feeling) for me, whereas for some Dhamma Wheel members it is sukha vedanā (pleasant feeling). On the flipside, listening to Pet Shop Boys is sukha vedanā (pleasant feeling) for me, whereas for others it is dukkha vedanā (unpleasant feeling).
By learning not to grasp, the Buddha never turned any feeling into dukkha... at worst, experiences would have been upekkhā vedanā -- equanimous feeling, neither pleasant nor unpleasant.
Insisting that the Buddha experienced dukkha is an error attributable to incorrect understanding of the subjective nature of vedana and a fatalistic over-simplification of what dukkha (dissatisfaction / dissatisfactory experience) constitutes.