Um maybe....firstly I am not familiar with the KLN89B GPS.
When you load the RNAV approach the GPS should recognise all of the available waypoints for that approach, including the missed approach holding point (WOLNH).I assume that you didn't have to press goto for all of the other waypoints? so why would you need to press it for the missed approach holding point? On the Garmin 430/530 at the missed approach point the GPS goes into a 'suspend' mode to allow the pilot to sort his/her s**t out, then the pilot must elect to continue with the missed approach. On the GARMIN 430/530 series this is done by pressing the OBS button. The gps then switches back into navigation mode and takes you to WOLNH
Is there a similar 'OBS' button on the KLN89B GPS?
My guess is that in order to load/activate the RNAV approach you had to either have been 'going to' YWOL or it was the last waypoint in your flight plan. When you hit the 'GOTO' button, the first thing it loads is the last place you were heading to, in this case YWOL.
Hope this helps
Alpha