If you're in the US, I wouldn't so much worry about losing your SB because the title is written on the label as I would be concerned about what's reportedly going on with the postal service right now causing backup and leading to more items being lost in transit. I wrote this on another site but I'll post it here as well. Take it with a grain of salt because this is just what I've been told - although today there have been a lot of media reports about delivery problems moving forward:
I live in Washington, DC and the other day I was down in my building lobby when the postal worker arrived and for the second straight day my building had no mail (he had mail to pick up, though). The woman working the front desk asked him what's going on and he said (in DC, at least) that the new postmaster general ordered the sorting facilities shut down for an entire day. He said the official word was cost cutting but that now they are so far behind in delivery that mail sitting in facilities could be delayed for weeks moving forward. Again, that's what a DC postal worker told me and I don't know if that only happened in DC, if it was a one-time shutdown, or if this will occur with regularity moving forward.