They all ought to be, but very slowly over billions of years.
Globular clusters are gravitationally unstable.
Their outer stellar population slowly drifts out into space while their cores become denser and denser until finally only a few binary stars are left in the core, and much of the original population has been slingshot into the distant halo regions, there to get stripped away by the tidal gravitational field of the Milk Way. I know of no instance where this slow expansion has been directly detected over human lifetimes. Return to the Ask the Space Scientist main page.