I was surprised by that ending (not Grodd but before that where the Firestorm guys had to leave). I was expecting Prof Stein to warn Barry not to trust Wells, or if Stein had forgotten I thought maybe Ron would have "seen" the memory of being drugged while merged and would tell Barry and Caitlin about it.
I guess I'm going to have to accept amnesia came along with that knockout drug.
I'm sure Wells played it off as "they hit you from behind with some kind of tranq while we were taking" and he just took his word for it.