Okay, I know NOTHING about Tama drums, but I DO know about Ludwig Downbeat snare drums. They have a very similar style of lug.
Initially, they are installed and are parallel with the shell. But over time, the pull from the lug screws causes the the holes in the shell to slightly deform into an oval shape and the lugs begin to turn like a steering wheel. Believe me, it doesn't take much to throw off the angle -especially when a lot of tension is applied...and especially-especially when the shell is thin and/or of soft(er) wood.
To really check this, you need to loosen all the lugs from the shell and then turn then to the proper parallel angle and re-tighten them -being careful to not over-tighten them (since they are diecast, they can strip out). Then put the heads back on and try to bring them up to tension. You will see the lug casings begin to "spin" out of alignment right away.
If this is a problem for you, then it is possible to shim up the oval-shaped holes. It might be a bit time-consuming.
Of course, if this drum was made in Taiwan, then all bets are off.
