Yessss, learned this one the hard way too, like most of my lessons :lol:
If it's important always try and pick your colours during daylight hours. Have also found in day light that all blacks are not created equal, you wouldn't think that there wouldn't much diff would you, but there sure can be, oh well it's meant to be patchwork.
Never mind it will prob fade with time and in a few years you may be quite pleased that you picked a stronger colour than you origionally intended :-)