I kept ending up in groups of two, sometimes three, then I noticed there was a pattern - it was usually me and a level 12-22 dps in the group.
I looked in my chat log the last time this happened and saw my log was recording other members being added and leaving the group right away, probably when they saw the lowbie dps on the group list. Which meant I could either leave the group right away too or get force ported in my group of two and try to manually restart the group finder.
At any rate the tool should not be force porting incomplete groups into dungeons, even if they originally started out with four members.
Another problem that really needs to be addressed is that group finder gets confused when people select multiple roles. For example this afternoon i was using group finder.. it made a group of 3 and instant ported us to the dungeon. I was tank and only selected one role - the other 2 selected two roles - both clicked on healer and DPS. This made group finder think we had 2 dps and healer with a tank.. it took 20 mins to find the 4th person.. instead of getting us the dps that we needed it got us an extra tank! So group finder was looking for a tank instead of DPS.. no wonder it took so long.. Clicking multiple roles confuse group finder and it has to be fixed!