Very very faint line....,am I jumping the gun/eyes deceiving me

Hi all, I never post on these, we are ttc baby 1 and I woke up at 3:30am desperate for a wee (which is quite normal for me) so I thought I'd poas whilst I'm at it and got this: I mean it's still early I'm only cd27 ad due in 3-4 days. But what do you think? Is it just a shadow? It could well be.