Should Catholics in a state of grace call themselves sinners? The Bible says our righteousness is a filthy rag(works) it also says we are the righteous of God in Christ Jesus. As a Catholic at a state of grace is it right to still call myself a sinner when I have been justified by grace taking upon me Jesus Christ righteous?
Being in a state of grace is defined as:


  Condition of a person who is free from mortal sin and pleasing to God. It is the state of being in God's friendship and the necessary condition of the soul at death in order to attain heaven.


However, the Catechism makes a distinction between sins as mortal or venial so it is possible to be in a state of grace (free from mortal sin) while still being a sinner (having committed venial sins). Indeed, the Catechism refers to one who has committed venial sin(s) but not mortal sins as a "sinner" despite being in a state of grace (emphasis added):


  1863 Venial sin weakens charity; it manifests a disordered affection for created goods; it impedes the soul's progress in the exercise of the virtues and the practice of the moral good; it merits temporal punishment. Deliberate and unrepented venial sin disposes us little by little to commit mortal sin. However venial sin does not set us in direct opposition to the will and friendship of God; it does not break the covenant with God. With God's grace it is humanly reparable. "Venial sin does not deprive the sinner of sanctifying grace, friendship with God, charity, and consequently eternal happiness."


One could perhaps claim to be not a sinner just after having received absolution (so that you are free from mortal and venial sin), but even so the Catechism uses the word "sinner" to refer to a person who has just received absolution (emphasis added):


  Satisfaction
  
  1459 Many sins wrong our neighbor. One must do what is possible in order to repair the harm (e.g., return stolen goods, restore the reputation of someone slandered, pay compensation for injuries). Simple justice requires as much. But sin also injures and weakens the sinner himself, as well as his relationships with God and neighbor. Absolution takes away sin, but it does not remedy all the disorders sin has caused. Raised up from sin, the sinner must still recover his full spiritual health by doing something more to make amends for the sin: he must "make satisfaction for" or "expiate" his sins. This satisfaction is also called "penance."


The Catechism could easily refer to the "sinner" who "must still recover his full spiritual health" as, for example, a "penitent", yet it nonetheless continues to refer to the person as a "sinner".

Therefore, I would still call myself a sinner even if I'm in a state of grace. Even if one has recently received absolution from confession, in honesty and humility it is probably not long before one commits another venial sin and can no longer claim to be free of all sin.