Lots of good commentary. To rehash and introduce a few things:
How could one even say it "should be" at say 1.20. Would that not assume (maybe wrongly) that prior valuation was absolutely correct? I mean, if current values are so "incredulous", how could we ever truly think they were accurate in the first place (and if so...for how long)?
And a poster was right in that, how could knowing it should be at say 1.20 even help you? It's at 1.4x. It could go to 1.60 before correcting. It could take 5-10 years before correcting "appropriately". And who is to say that in whatever time it takes to react appropriately that something else doesn't happen and completely change that original opinion (and possibly very harshly). That sort of thinking (that xyz should be at xx) is why so many lose money.
Also, what is your time frame? What's your average holding time. If it's days (or less), you need not even ask such questions). If it's weeks/months/years, you've probably had this sort of question every...well...every few weeks.
You always need to be aware of the long-term picture, but you need to trade the short-term.