They feel a need for additional skills or training

As time goes by your more experienced staff may start to feel left behind. This is normal, but it can be unsettling for people who have been used to being the ones with experience and authority to find the pace of change is accelerating too fast for them. It may suggest a need for training, which the more experienced members of your staff may not be expecting, but it may also indicate that the culture at work does not respect the history and achievement of older staff members.