Is it normal for instantaneous GLOC to occur at 5 G's? Is it normal for a trainee to have an instantaneous G-force induced loss of consciousness (GLOC) at 4-5 G's in a light military trainer aircraft like Socata TB 30 Epsilon, after doing a manoeuvre sequence?
That sounds really unlikely to be a G-LOC.  That usually happens at much higher loadings after 3-4 seconds of straining.  The counscious and cognitive centers of the brain take a few seconds to shut down once the systolic and diastolic pressures hit zero in the brain.  It may be an indication of another underlying medical issue.