Ukemi Waza: Pain in Mid and Upper Back

Although it has been years since I trained in Aikido and I am no longer a member of any particular dojo, I can't resist practicing what my old sensei called "rear sitfall" and what "Best Aikido: The Fundamentals" names "Back Breakfall" or "Ushiro hanten ukemi." I think we all know what I've been talking about. I just wanted to make it abundantly clear. Both studios at the JKD school I go to have padded floors: One has tatami and the other has these padded jigsaws.

I have become (in)famous at that school by doing a breakfall when I go to warm up before class. Part of it is practicality: I don't crouch down quickly so I put Sir Isaac Newton in the driver's seat. He gets me there quicker. And of course, part of it is having fun/showing off. But lately, I have noticed pain in my mid-to-upper back on some falls. It usually happens in Silat class when he has us do some falls and throws as a part of warmup, But tonight it happened when I took my express elevator to the mat before kickboxing class. On a scale of 1 to 10 it was 0.1, but it was there.

So, my question is, how concerning should this be? Is my technique a little sloppy? Am I out of "aiki-shape" after having been off the aiki-mat for 3 years and counting? Or could something more serious be happening?

Could use some experienced opinions.

There's a fair chance you just have some typical vertebrae misalignment. That can cause undue strain of the back muscles on one side of the body or place pressure on a nerve, etc. I'd personally recommend seeing a chiropractor. If you can find one near you with a digital x-ray machine, that would be a bonus in my mind.

I know that some folks have had bad experiences with chiropractors, as quality control in that field does not seem to be as high as typical medical fields, and there are a small number of super-quacks out there that give the rest a bad name. I have my own criteria for what generally makes a good chiropractor:
1. Will not claim to be able to fix conditions that you yourself can't see an obvious connection to.
2. Knows his/her limits and has no problem referring you back to an M.D. if the issue is outside their specialty.
3. Will not endorse homeopathy.
4. Will not try to force herbal remedies upon you.
5. Improvement should be obvious after the 2nd appointment (first appointment possibly not so much; expect 3-5 appointments for typical issues)
6. Will not be pushy about trying to get you to schedule additional appointments after the problem seems to have cleared