You should be OK. I doubt that a quarter pack of dry yeast will dramatically change your beer. My guess is that much of the activity you are seeing is the WLP300.
As a rule of thumb, you should have made a starter. I've made a lot of really good beer just pitching the vial, but you do run the risk of underpitching.
Brody's Brew House
Primary: Spiced ale
Planned: Butternut squash & gala apple harvest ale; brown ale or porter; barley wine
In the fridge: Dogfish 60 minute; Imperial Stout