  Belle report data on Upsilon (5S) -> Upsilon(1S,2S,3S)-piplus-piminus and
chi_b(1P,2P)-piplus-piminus; they observe peaks in Upsilon-pi and chi_b-pi
consistent with J^P=1^+. They interpret the peaks as molecular states
Z_b(10608) and Z_b(10653). Their masses are just above Bbar-B^* and B^*bar-B^*
thresholds at 10604.6 and 10650.2 MeV. An explanation in terms of cusps at
these thresholds is presented here. The product of the rising phase space for
Bbar-B^* and B^*bar B^* with the cusps creates peaks a few MeV higher in
Bbar-B^* and B^*bar-B^*, and these peaks can de-excite to
piplus-piminus-Upsilon(1S,2S,3S) and piplus-piminus-chi_b(1P,2P).
