In my opinion, this is probably completely coincidental. You probably had this dream because you were thinking of better times, or people you care about.

Though the shared dream part intruiges me. Perhaps the two of you have an extremely special bond? [Just my little extrapolation: You two probably have a heightened 6th sense, in the ESP form of Telepathy through your dreams.]

If you have more dreams like this, where it is shared, I'd love to hear about them.