Learning How to Test Tubes with Sencore - A Few Questions

[vintage.digi]

Okay, so I made it as far as testing the tube for the BVM as was my goal. My main concern was shorts and I didn't see anything indicating shorts either G1 or H-K shorts.

One thing that I did note however, is that on the cutoff and low tracking test, the voltage seemed to slowly drop. It was appearing to get a little more steady over time, but I wasn't sure how long it was safe to leave the tube hooked up to the tester. I know that you're expected to leave the monitor on for 30 minutes before doing any calibration, so it does take a long time to warm up.

Would a meter slowly dropping during the cutoff and low tracking test be of concern? Should I let this test run longer to see if the tube eventually stabilizes after warming up?