Red oak gets this way, especially if the grain is not quite clear. Never used it on a canoe, but plenty of other projects - watch which way the grain is going.
Going way back to my SOF built kayak in High School (mid seventies). Vinyl-ester resin, where I should have just varnished. In fact - the whole resin and glass thing. Didn't know, and had nobody to mentor me.
My earliest resin and cloth experiences were based a similar “Didn’t know”. For few years I was reluctant to tackle even the smallest cloth and resin repair and would ask an “experienced” friend for help.
His “experience” was based entirely on auto-body repairs, using polyester resin, E-glass and Bondo from the auto supply shop. Not my proudest boatwork.
He was pretty good with autobody stuff though. We came off a trip when he backed his wife’s van into a rock wall, crumpling one fender. Before he went home he brought it up to my place, pounded out the dent, bondo-ed the wrinkle and painted it a matching white. He even hand painted in the missing section of red pin stripe.