Back again

Is this normal or should I be concerned.
Big Bud
16 days old.
Fertilized one time, three days ago with 12-4-8.
Bottom leaves turning light green with some small browniing area in center of leaves. Leave curled up a little on ends. This issue was occuring prior to fertilizing. All other leaves and nodes green and lush. Trying to avoid any more calamities..... It was transplanted today.
Miracle Gro seed starter mix with 35% perlite. (Seems to be doing very well)
All other mixes I have used have killed my seeds several times (I'm sure my fault).
Any help will be greatly appreciated.
Eggbert

Nute burn man.. Use 1/4 the dose of nutes that is recommended for their first feeding if not the first two or three feedings..

Was it in a small pot? make sure the water/feed is 6.5 PH and give the medium a flush every 5th feed to avoid salt build up which looks like you had.

2 weeks old is too early to feed IMO, with that soil especially.

Thanks for the input folks.
I did not mention the nute was 1/2 strength.
Eggbert