Hey mate, they are just the the embryonic leaves (cotyledons). It is perfectly normal for these to wilt or fall off, their purpose is to give the plant enough energy to grow real leaves and then they are of no use, so dont be worrying. Glad to see your growing your own instead of buying that dirt weed were overrun with here in Ireland. Mine are 11 days old from seed and have their second set of true leaves, they will shoot up real fast in the next week. Get yourself one of them 220w cfls (â?¬50 in get up and grow Dublin) and you will be amazed at the speed of growth, cant rely on the poxy Irish weather to grow em... global warming my arse!