Well, I gotta say - you guys are not helping my case
at all!!!
I have always noticed a plastic-y taste for most everything that gets packed into a plastic zip-top bag (it's worse with the store brand bags than it is with the Ziplocs, but I still notice it with Ziplocs). This happens with just about everything - chips, sandwiches, cookies, bread, etc... And even if it's only in there for a few hours (from when it's packed in the morning until lunchtime).
DH has always sworn that I am crazy and it's all in my head, but I know what I taste. Our compromise that we have reached is that he uses zip-top bags when necessary, and I will wrap whatever it is in press & seal. I don't notice the flavor issues with the press & seal. Especially with sandwiches and bread type stuff. We use the Glad containers for everything else.
This came up last night because we had baked some cookies and needed to store them. DH wanted to put them in a Ziploc, but I wouldn't let him because of the plastic-y taste issue. They wound up wrapped in press & seal.