I have done a little bit of research and I found
this piece of code with good commentary.
// utxoNursery is a system dedicated to incubating time-locked outputs created
// by the broadcast of a commitment transaction either by us, or the remote
// peer. The nursery accepts outputs and "incubates" them until they've reached
// maturity, then sweep the outputs into the source wallet. An output is
// considered mature after the relative time-lock within the pkScript has
// passed. As outputs reach their maturity age, they're swept in batches into
// the source wallet, returning the outputs so they can be used within future
// channels, or regular Bitcoin transactions.
As you can see, since the CLTV time-lock didn't expire, you had to wait until it was "incubated".
Here you can find a graph which will help you to understand it more easily.