No, I don't think you need to worry. If a hen is acting normal then everything is ok. Please remember that these hens aren't laying machines but living breathing poultry that don't produce eggs 24/7 every day of their life.
Some problems can occur within the flock that result in less eggs collected, however i don't think you have those problems.
Keeping the feed high in protein is real important once the hens have been laying awhile. The constant laying of eggs is stress to the hens internal system, so helping them with a good diet is important.
Commercial egg people cull the flock every 18 months or so. Keeping our backyard flocks healthy and happy and proving they are way wrong with their thinking is why I do this... My older flock, not only being heirloom and not able to provide the commercial egg indistry the eggs they need on a daily basis is priceless.
The quality of life my hens live on a daily basis is exactly how God ment it to be.
bigzio