That's the best way to use that yeast, IMO. Hopefully you lowered your fermentation temperature so that you'll get a nice clean flavor out of it. The reason it's going crazy is that, even if you used one packet for the 7 gallons (under-pitched count for lager), you ended up with about 2.23 billion cells per milliliter/Plato gravity point for the second batch. Good lager yeast count at cold temps is 1.5 billion c/ml/P. That's a 50% overpitch at lager temps and well over 100% overpitch if you're fermenting at ale temps (over 60 degrees). If you used 2 packets, obviously you're 3 to 5 times overpitched.
When I use that stuff, I do a 5 gallon fermentation with 2 packets and let it run at ale temps just build up yeast. The resulting beer from the starter batch is lager-y but not without some fruity yeast contribution (more like a Kolsch or a very clean Blond Ale). Then I use the resulting slurry for a 1/2 barrel batch fermented cold. It's just barely the count I need according to the calculator, but it works like a charm.