4.3 vortec engine noise??

i have a 97 s10 with a 4.3 vortec in it got about 104000 miles on it. it just started making a ticking noise after drivin it for a few minutes. but doesnt do it after first starting it.what could this b? thanks

SOUNDS LIKE YOU ARE LOSING OIL PRESSURE AND THE LIFTERS ARE MAKING NOISE.

my oil pressure never drops... could it be a header leak cuz i have a set of headers on it??