If you dream old days, its dream interpretation is that you have nostalgia for your past.
You might have encountered an experience during your day, that reminded you of your old days and this refreshed your memory of the past. This would trigger the resurface of the particular memory of the old days.
If you had a threatening experience during your day, the stress and shock may trigger a replay of an old memory that is either similar to your new experience, or a reminder to heed the warning from old lessons learned.
