I had my EGR valve and MAF sensor replaced under warranty last week. The car seems to be fine now

The garage do still think there is a problem with an injector, and a different garage report a leaking injector too following my 72,000 mile service a few days ago.
Does anyone know if injectors are covered under the 3rd year warranty? What is the consequence of having a leaking injector? Will it just burn more fuel or could something far more major happen?