Should I worry at all?

my plant Ice (grown from seed) first had the tips of the first leaves go a little yellow, I put it down to either heat excess or chlorine in the water, well ive adjusted my water and the light, it seems healthy enough sprouted two more leaves and is just now sprouting 4 more, but yesterday I noticed one of the lower round leaves had wilted and it came off today.

should I be worried at all? it seems healthy for the most part.