  We numerically investigate the propagation of a self-compressed optical
filament through a gas-glass-gas interface. Few-cycle light pulses survive a
sudden and short order-of-magnitude increase of nonlinearity and dispersion,
even when all conservative estimates predict temporal spreading or spatial
breakup. Spatio-temporal distortions are shown to self-heal upon further
propagation when the pulse refocuses in the second gas. This self-healing
mechanism has important implications for pulse compression techniques handled
by filamentation and explains the robustness of such sources.
