Assembled my first upper today. When I put the bolt/carrier in it seems to rub on the gas tube. Should I try to adjust the tube or is it ok?

It is always going to "rub" a little.
That being said take the bolt out of your carrier slide the carrier in and out of your upper and adjust the tube to get as smooth as possible engagement.
As long as you have it centered in the bbl nut minor tweakage should be all that is needed.
If you watch real close you can see which way it deflects when the carrier slides into place and or lay you finger on the tube you should be able to feel it also(real easy with standard HG).
Adjust accordingly.

Quoted: Assembled my first upper today. When I put the bolt/carrier in it seems to rub on the gas tube. Should I try to adjust the tube or is it ok?

The gas tube should free-float through the barrel nut. The only contact with the rifle should be the gas tube roll pin in the front sight base. It sounds like your barrel nut is touching the gas tube and deflecting it to one side.

Quoted: Quoted: Assembled my first upper today. When I put the bolt/carrier in it seems to rub on the gas tube. Should I try to adjust the tube or is it ok? The gas tube should free-float through the barrel nut. The only contact with the rifle should be the gas tube roll pin in the front sight base. It sounds like your barrel nut is touching the gas tube and deflecting it to one side.

+1 I would try to tighten your barrel nut a little more.  Seems like the nut notch and tube aren't lining up correctly.  

or the barrel could be slightly canted, which in turn cants the FSB/ gas port causing the tube to rub even when the barrel nut is properly alligned.

Take the upper off and remove b/c/ch.

Inspect the gas tube "nub" visually.... is it cocked to one side or the other?  If so - the most likely cause is that when you tightened the barrel nut - on side of the barrel nut lugs is pressing the tube over.... causing this issue.  Sometimes, it can be a bent gas tube....

If you are sure it is the barrel nut... you can adjust it to better "float" the tube.... or you can bend the gas tube in front of the receiver... if the offset is very slight.

Then, remove your bolt from the carrier.  Take the carrier and insert it into your upper.... work it back and forth and watch where it hits the tube, and which way the tube is moving.  Some contact is inevitable.  You just dont want it excessive.... because you will wear the carrier gas key prematurely.

I got it to where it barley touches. Thanks for the info.