Brief upper back "pain" during longer paddles

This isn't what I'd call traditional back/neck pain, it's more like a feeling of having been in an awkward position too long and and I feel it for a second or two when I adjust to a more upright position. I'd estimate it was around the C7, kind of between the shoulders - but that's just from memory. I've only ever experienced this a handful of times, and the rest of the paddle was fine - I've been meaning to ask about it here.

Does this just mean I need to be sitting more upright, or keeping my head up? Curious if anyone else has experienced this. It's not something I'm too concerned about, and I don't experience it on my daily 5 mile paddles - only when it's 8 miles or more.

Is it kinda like short lasting sharp pain that comes out of nowhere and disappears quickly?
I used to get that but a bit lower, roughly between shoulder blades. It got gradually better as I progressed with my weight training and eventually disappeared.
I think was muscle atrophy. Our backs are pretty complex and some regions may end up under used and weaken.
I think what helped is reverse rows with a barbell. It did take some time to condition though.
Your situation maybe different of course. Maybe get it checked out to rule out joint/disk issues and get a rehab exercises going?

Yes, that sounds like the same sensation: it's sharp but gone within seconds and everything feels 100% fine after that (doesn't feel sore or hurt at all) - and now that I think about it, maybe describing it as being between the shoulder blades is more correct. The conditioning makes sense - I'm going to try to get a daily lift in, and keep an eye on it.

If I could relate it to prior experiences, I'd say it's similar to when I've had my neck/back in an awkward position for a little while (i.e. having my neck cocked and looking  over my shoulder), and then it hurts for a second when I return to a normal position.