"Myslím, že jsem tě viděl v mracích."

Translation: I think I saw you in the clouds.

[EinatAdar]

Is this a common expression in Czech or just a strange saying to help us remember?

[VladaFu]

No, it is not common. Sounds like some poetic sentence.

[CathyBowde1]

I was thinking that too. Could be someone describing a vision, or that they were watching the other person flying a small plane.