[Response time is showing zero on]

Hello Everyone!
I hope everyone is enjoying an international freelancing day and also doing great.
I have a question and any answer or suggestion in this regard will be appreciated.
I am a level-one seller on Fiverr. I have responded to every single message of buyers. For two weeks my response time is shown as zero, previously it was shown as 1 hour.
So I am confused about whether the minimum response time is zero hours or one hour.
Should I contact Fiverr support if this is not normal?
Thanks!