[Is late responding to a buyer with no order placed a violation?]

Hi,

I late responded a client after the order was completed (I was assisting them on something as a favor - and I didn't notice their last message). 

Yesterday I woke up with a warning from Fiverr. 

What do you think about this? I've read the TOS I didn't find anything states that I must stay responsive to clients with no order placed. I'm here just to make sure.