Crazy ATCC lady eh? CHO cell issues bleh!?

That can be a problem; I only worked with CHO cells for a short time, many years ago, so I can't say if this is a problem with them. Your experience may or may not be useful - you're assuming that the vials you got now and the ones you got then were the same; are they? Same concentration and everything? Some lines need a certain initial concnetration to get comfortable. On the other hand, taking that long to settle down does sound a bit suspicious. If you have any of those vials left, perhaps you could try her recommendation and see if it makes a difference. Otherwise, you probably want to ask for a replacement. Remember, politeness pays even when you think you've been wronged! An ounce of schmoozing often gains you a pound of assistance, where being a jerk just gets you hung up on.