Is it safe to use hot air on SMD LEDs?
There's no way to be sure about potential damage without knowing the part number of your LED, which is needed to obtain its datasheet. The datasheet will outline the temperature specs of the LED (including max storage temp and max operating temp) as likely also its performance characteristics at various temperatures. I picked three random SMD LEDs from Digikey as a small sample (1 2 - the third is 160-1446-2-ND, but I lack the repu to post the link), and they have operating temps up to 80-85 degrees C. Max storage temp for one is 120C, but the other two max at 85C. Because of this variation, you need to know exactly what the specs of your LED are, but you'll might be cutting it a bit close. Some datasheets outline reflow info for their part, so your best method will be to follow that guide. Personally, I wouldn't be very worried about doing what you're doing as long as you have back up LEDs just in case, but if you don't have extras and/or can't risk damage to the PCB, then you'll do best to check the datasheet for all the info mentioned above.