The adjusters may be fine, but as your oil gets worn you may be getting more trapped air in it. As the adjuster leak down the oil system then fills them back up again with pressurized oil, if that oil has air in it the adjusters will be noisy new or not.

Newer adjusters may leak down slower and not get as noisy, but the real issue is your oil. It may be getting contaminated a bit faster than when your motor was new if your ring seal is not as good or your driving cycle is more severe.

As others recomended go for an extra oil change. You may want to consider getting your oil tested at a lab to make sure that its not getting contaminated with a slow coolant leak or a leaking air filter.

Kevin C