My hunting buddy & I went to the range to sight in our 30.06

His first shot was about 6 inches high, so he adjusted it and got
good group. Then I shot awhile.

His barrel had cooled and he decided to shoot again, his first shot was again about 6 in high. with out adjusting, 2nd shot was pretty close to aim point. we were out of time and had to quit at this point.

Does this sound like he just happened to "pull"thisshot, or this gun doesn't shoot a cool barrel well, or could it be the ammo?

Any ideas appreciated!