I'm working on a dining table (~ 40" x 70") and I'm confused about why it won't stay flat. I've built it using 8/4 walnut that was dried (properly stacked and stored) in a garage for 7 years. I did everything I thought to do during the build - alternate growth ring direction, used breadboard ends, careful edge glue up, glue up in stages, and gave it plenty of time to acclimate in between gluing sessions. Before and after installing the breadboard ends, I flattened it with planes. Now, about a week after installing breadboard ends (and the last flattening), it seems to be cupping. It's not a lot, maybe 1/8" in the worst place, but I'm confused on what I should do next. I don't want to do finish prep and finish and have it move on me again. I'm pretty new to this, is this normal? What should I do next? Any thoughts/suggestions?
For Reference:
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