  The hierarchical triple system containing the millisecond pulsar PSR B1620-26
in M4 is the first triple star system ever detected in a globular cluster. Such
systems should form in globular clusters as a result of dynamical interactions
between binaries. We propose that the triple system containing PSR B1620-26
formed through an exchange interaction between a wide primordial binary and a
{\it pre-existing\/} binary millisecond pulsar. This scenario would have the
advantage of reconciling the $\sim10^9\,$yr timing age of the pulsar with the
much shorter lifetime of the triple system in the core of M4.
