That because a miner found a solution too fast for transactions to be included?
Discussion
kinda, it takes a couple seconds to get the block template so hashers start working on an empty block. Every once in a while a nonce is found in those few seconds reminding us that every time a new nonce is tried has the exact same chances of being valid.
Why can't mining pools have a "backup" template filled with 1sat/vb TX ready to go for those first few seconds?