Hi Smurggle, I honestly would not worry too much about the coat just yet :) Below is exactly what the breed standard states on this.
Coat
>Distinctive feature, short dense without wave or feathering, giving fairly hard feel to the touch; weather-resistant undercoat.
This was another of the slight faults that I had with Tia, but since her 1st season and the loss of all her puppy 'fluff', her coat has developed really well without a hint of wave. I know some Labs tend to keep a slight wave, and although it is highly undesirable, I have seen some very good labs in the ring and this fault has not diminished their overall placings. I suppose it really depends on how wavy the coat really is, there are much worse faults seen in the ring at the moment. :(
What I am really saying, is give showing a go if that is what you want to do. None of us have that perfect dog, although they are perfect to us :D
Kay