"Does ANYONE think there's a chance my batch might have been too old?"

No but you never know unless you tested it yourself beforehand. They have always insisted 18-24 months. But to be safe, you can easily buy some drug adulteration test strips to put your mind at ease next time. They only cost a few bucks. I keep some of them and a spare bottle at my house at all times now. Also remember they will swap you out a new bottle if you have concerns in the future.