Hmm..I think I killed this thread almost a month ago, but I'm going to go ahead and update it just for my peace of mind
I received this reply from Merrick's customer service yesterday:
Thank you for your inquiry. We have not changed our formula for Puppy
Plate. Unfortunately, gas can be caused by a number of different
factors. Since it's difficult to determine exactly what is causing the
problem, I would be happy to send you a coupon for a new bag. Perhaps
you could throw away the bag in question, and hopefully you'll have
better results with the new bag. Please reply with your mailing address
and I'll get you a coupon sent out ASAP.