Yellow seepage on day of lockdown

[4hchickmama]

I have 3 duck eggs going on lockdown today and I just candled everyone before putting them in to make sure we didn't have any that weren't viable, and one of the eggs has a yellow seepage internally that I can see when I candle. The duckling inside is definitely alive...I can see it moving, but I am unsure what the yellow means. Any ideas? Is this a bad thing?