What kind of trap are you using? Are you seeing any adult SHB in the trap?
One or two larva are probably not much cause for concern if you have a lot of bees and you are not seeing any comb damage upon inspection. If on the other hand you can see some comb damage, then I would be concerned that a lot of the larva are escaping your trap.
If you are only seeing one or two adult beetles in the hive, then the bees are probably doing a pretty good job of keeping them "at bay". I have DE (diatomaceous earth) in my traps and I am still seeing alot of dead and dying adult SHB's in the traps and once in a while I will see one or two small larva in the trap as well. Generally I only see one or two beetles in the hive on inspection and if I wait and watch long enough I will see the bees "throw" them to the bottom where they usually go through the SBB into the DE (never to return).
We recently had a lot of rain and cooler weather in our area and they seems to bring the SHB's into the hive more. When it hotter and dryer I see fewer of them.
Keep a close watch, things can go bad quickly if the SHB's get ahead of the bees, especially on a new package (I have lost three new packages this year, SHB's contributed heavily to their demise).
"The UNKNOWN, huh? That would be SNORBERT ZANGOX over in Waycross."