In lieu of a quarantine tank at this point, I still suggest that you have the LFS hold your fish for a period of time before you take it home.
Triggers are not terribly apt to carrying disease, so it's not the most horrible thing in the world to purchase without a quarantine tank, but it still should be a part of your normal regimen, first to allow you to isolate and treat any illnesses that new arrivals or sick fish require, and second to protect your established tank.
I wasn't a believer in quarantine myself until I killed an Emperor Angel, Red Sea Sailfin, and a Red Coris Wrasse (all pretty expensive fish) because of one Blue Hippo I didn't bother to quarantine that brought in Velvet.