If all your inserts make use of the sequence, and you never alter the sequence, then this should never happen (unless, that is, 34 other inserts happened between when you inserted and when you checked the max). Be extremely careful of selecting max(rowid) when you have concurrent transactions; it's entirely possible that some other transaction has consumed a value from the sequence but hasn't yet written it to the database (at least, not in any way that your transaction can see), which means you risk resetting the sequence too low.
ChrisA
May be it was an artefact because i was using the same database from command line and thru php ? because, right now, i do only : INSERT ... RETURNING rowid; and it works well from php... i did quit the command line by "\q" in between...
