The heads that are at the lowest point of the run will always seep water for a few minutes until the line is clear.
If they always leak water that is a different story, and it means that the zone valve is leaking. A leaky zone valve can be the result of pebbles or grit preventing the inner diaphragm from sealing or simply a bad diaphragm. Extremely high water pressure could also cause water to sneak past the zone valve.
Hey, thanks for the information. First time ever having a sprinkler system and may have a lot of questions. It all seems pretty simple just need to educate myself. Any suggestions on any good books or manuals about sprinkler systems. Thanks if you have time to answer that would be great if not thanks
Your local irrigation parts distributor may have that info, and you can keep posting questions here, as well. Take a look at the archives on this site, and you will learn a lot.
All the manufacturers....Rainbird, Toro, Hunter, K-Rain, Orbit, etc. have great websites. Many retail and supply stores provide excellent free handout literature.