Could spark plugs jump out if coil pack is not tight

No. Some of the Triton engines with aluminum heads had spark plugs blow out like bullets but Ford figured it out, the combination of aluminum and only 6 threads holding plug in....most heads/plugs have at least a dozen threads to turn for a plug, but nothing to do with coil pack

Are you sure you had them tightened properly when you finished the job? I take it one or more have blown out or you wouldn't be asking. I think you need to pull them all and re-install them at the proper torque for your engine.

I dont think the plug would come out if the plug was screwed in right wiith your plug socket an extension and a good ratchet

Well, the 5.4L engine seems to have cured the problem... the d**n plugs seem to seize in the threads and strip them when you try to remove them. I went to Ford to have them replace my plugs at 150,000mi knowing I didn't want to try it. I got a price and said "let me pay you now so I can just run in and get the car". His reply, "there may be additional problems the will cost more!" So the dealer will make more money because Ford screwed up.