By all means get the drive replaced: if you ever see a SMART warning*, replace the drive ASAP (well, back up your data first, BEFORE the drive fails!).
Apple should be able to replace your drive at the store, and it shouldn't take long, probably 2 or 3 days turnaround.
tooki
*It's my understanding that SMART keeps a log of all problems the drive finds. When you use an app like DiskWarrior, it clears that log, so an immediate subsequent test will show nothing. But normal use will again find errors, and they'll be stored until the next time you run a test.