I believe what you're refering as "4 ft" is the keel line. The stem is end(s) of the boat from the tips to the keel line. (about 20") If you're saying that your keel line where the boat starts to thin out as it approaches the bow has a bit of a wobble in it, I wouldn't worry about it. I would do some sanding with a sanding board and do the best you can to get it straighter. If you're worried about getting to thin with the wood, you can always reinforce the area from inside with a little extra glass. That's actually a very strong section of the kayak. Epoxy tends to puddle there when you glass the inside making it very strong.

Since Ken lives near you, you have a great advantage. Check his out and maybe he can look at yours. Do the best you can to straighten it out. The boat will paddle fine. Be prepaired however, Ken's boat is unbelieveable.