Don't know if it sends one no-sim, but it's likely. During reflash, phone goes offline at least to update GSM modem firmware so it's likely it's sent after the first boot. If it fails, it will be kept in the outbox at least, if not retried.

But do try, it's be nice to see if it at least pops if it's failed or delivery failed. I never saw anything like that and hiding that as well as the SMS IMO proves the intent to hide the sms as opposed to, you know, slipped their minds