On the contrary, Elad--that is a very positive sign! Your seedlings are perfectly fine--that transition from bright sparkly green to sometimes reddish then to brown is normal. It happens when the skin on the trunk starts to mature.

Over-exposure to the sun normally shows up as a kind of blanching on the leaves. My sister grows them where daytime temperatures go up to around 36C, full sun, in high summer. I don't think that's even close to the extremes they have to put up with in the wild. I once felt 44C in Phoenix and that was very ouch!

Congrats, you'll have a forest of these things pretty soon.

Pagan

Hi Pagan,
I'm terribly sorry for the late reply...
Thanks for your comment!
You are absolutely right, of course :)
My seedlings are now looking great, about a month and a half old, most have 2nd and 3rd set of leaves, and are ready to relocate soon to their new home out of the 2cm cup they're in now.
Will keep updating :)
Elad