You said the wood warped. If this is the case, and there's actually a gap between the wood and laminate, then you're going to need caulk. Urethane just won't cut it.
If you do caulk, remember that silicone caulk can't be painted, but acrylic latex caulk can.
If you go into your kitchen, or maybe bathroom, you'll likely find laminate, and there will probably be caulk at the back and side edges. Clearly, caulk is commonly used with laminate to keep water out. You can do it tastefully if you're careful.