here is a litany that may help you understand,
**Litany of Humility
(Composed by Cardinal Merry Del Val, The Saintly Secretary of State to Pope St. Pius X)
O Jesus meek and humble of heart, Hear me.
From the desire of being loved, Deliver, me, Dear Jesus.
From the desire of being honored, Deliver me, Dear Jesus.
From the desire of being praised, Deliver me, Dear Jesus.
From the desire of being preferred to others, Deliver me, Dear Jesus.
From the desire of being consulted, Deliver me, Dear Jesus.
From the desire of being approved, Deliver me Dear Jesus.
From the fear of being humiliated, Deliver me, Dear Jesus.
From the fear of being despised, Deliver me, Dear Jesus.
From the fear of suffering rebukes, Deliver me, Dear Jesus.
From the fear of being calumniated, Deliver, me, Dear Jesus.
From the fear of being forgotten, Deliver me, Dear Jesus.
From the fear of being ridiculed, Deliver me, Dear Jesus.
From the fear of being wronged, Deliver me, Dear Jesus.
From the fear of being suspected, Deliver me, Dear Jesus.
That others may be loved more than I, Jesus, grant me the grace to desire it.
That others may be esteemed more than I, Jesus grant me the grace to desire it.
That in the opinion of the world, others may increase, and I may decrease,
Jesus, grant me the grace to desire it.
That others may be chosen and I set aside, Jesus grant me the grace to desire it.
That others may be praised and I unnoticed, Jesus, grant me the grace to desire it.
That others may be preferred to me in everything, Jesus, grant me the grace to desire it.
That others may become holier than I, provided that I become as holy as I should,
Jesus, grant me the grace to desire it.**
i suppose it may not be considered sinful if you do not act on it or dwell on it pridefully,
but if you are doing your best and are honest and hard working, then there is nothing for you do worry about, if your boss isn’t appreciating you for the good job you do, then that is his problem, and he will not change his feelings unless he himself realizes it,
just do your best and that’s all you need to do, if your boss doesn’t appreciate you, you know God will, and when you’re working to please God and not those around you, then you are serving someone much higher then your boss, and your reward will be much greater,
well, we’re also told that when we do receive praise and compliments from others, that it is much more honest and humble to give those praises to God, because we are only His created beings, and all is truly His.
well…i don’t know if what you’re asking is sin or not in your case, but a sure way to find out is just to ask your priest.