Possibly - I don't have any sense of the desirable tension level, it just sort of ended up with most spokes being 20-21#, so I fiddled with the few that were lower (there were a couple in the 18-19# area after truing) and brought them up while staying true.
What determines the ideal tension? Does fewer spokes inherently mean higher tension?
Fewer spokes require higher tension. Mavic recommends 110kg on their rims. You should be able to use more. Did you stress relieve the wheel when you built it? If it were overtensioned when you squeezed the paired spokes the rim would have taken a curve.