I am not an expert, but all the bills for which I heard this were being amended. I believe they vote on amendments, then send the bill out for printing and order it back to the daily file (agenda, basically) at whatever reading it was at prior.
In CA bills have to be read (title of the bill and subject announced) three times before a vote. After the first reading it's assigned to committee. The second is just announcing it. On third reading they vote. Each reading must be on a different day and a month has to pass between introduction and final vote. These rules can be suspended with a 2/3rds vote.
Many of the bills were on third reading, but because they were amended, they have to be re-printed and then put back on the daily file and be read on third reading again before a vote.
So, basically out to print and back in file means "consent to be amended and able to be voted on tomorrow"
As of 10/10 the Governor has 121 bills left on his desk to sign or veto by 10/13.