ticking sound on start up

Hey guys whats going on, I have a 00 gt and its pretty stock for now , I have both a o/r h and a x pipe not on the car at the same time(i figure someone will crack on about that), magnaflows, k&n, bout it for power mods, recently i have been noticing a ticking sound when i start the car , it only ticks for about 15 secs. it really bothers me cause i have no clue why its just all of the suddon doing this , once the car warms up it doesnt do it, any suggestions on why this might be happening, and couls it lead to something serious.thanks for any info..Jayson

the sound is coming from theengine on start up and it goes away after a few sces. car has 70,xxx miles on it , should i get a ford dealer and get it tuned, the problem started when i wasnt paying attention and ran 87 oct. gas , i never do that , but ive been running 93 since and it still ticks on start up on a cold engine, any suggestions?? thnks Jayson