Change in joining date

Hi, I was about to join Accenture on 25th November but today after receiving the joining office mail I got another mail after an hour or so with a change in joining date to 28th November which I accepted on portal. What could be a possible reason for this change as I have already accepted a new offer letter sometime back with my desired location at Accenture and also all workday and onboarding links were not working for me. Is it completely fine as per process. Just confirming. Thanks in advance!!