Yes this is normal. My Jag moves sand around and keeps his 'spot' behind a log completely clean of any sand. You're going to love him...mine has been my favorite fish for a long time. They're such characters.
Since no one has mentioned it, you are correct on needing an upgrade. Incorrect on the tank size though. A male jag is eventually going to need a 6' tank minimum. I recommend skipping the 75 gallon upgrade and go straight to a minimum upgrade to a 125 or 135. Both of those have the same footprint (6' x 18") but one is 23" and the other is 25" tall. It's not all that much more maintenance than a 75 either.
Does anyone disagree with that?