starter foamed a lot when shaken, does that mean it wasn't done?

Just pitched my first lager, and the starter foamed like crazy when I shook it up before pitching it. Does that mean it wasn't done fermenting? I had it at room temp for about 2 days, and in the fridge (50 degrees) about 10 hours.

Also, it reeked of butter, so yay, I now know what diacetyl smells like! It was down to under 400ml after decanting, so I'm hoping that quantity won't matter. I pitched with the wort at 51 degrees, with the freezer set for 48, hoping to avoid doing a d-rest, since I'm worried i'll be to busy to catch it when it's 75% done or whatever... plan is to just wait 2 weeks, make sure it's done, rack, and lager.

It foamed a lot when shaking due to CO2 coming out of solution... as long as you gave the starter a day or three, it is most likely done.

I usually swirl it for a while before i pitch, so im not pitching foam, just liquid.