Base-emitter reverse breakdown and current
Sustained reverse breakdown of the base-emitter junction of a BJT will cause gradual degradation of HFE.
In some cases it can also cause unusual photo-emission effects where light coming from the junction in breakdown can cause photo-current or even photovoltaic generation in other junctions.
Keeping the current low reduces the rate of decay so that is in your favor.
Are Reverse Biased transistors stable?