Puzzled

Hmmm...Puzzled by something I read this morning and I want to "investigate"!

In Psalm 51:11, David begs God not to "take Your Holy Spirit from me".
Curious what He meant since the Holy Spirit technically wasn't given to us until Jesus was about to leave the earth...Hmmm!!!
Gonna check some commentaries, but this is intriguing to me!
I've always been taught that David was a man after God's heart, but is it possible that perhaps David had a unique bond/gift/closesness with God to where he had a sense of the Lord's Spirit even those many years before?

I just started thinking...!  SCARY I KNOW!