Alright, I was stripping my one female Lab. chisumulae, and of the first 5 that came out, 4 were fully developed and free-swimming. The fifth one, however, was like a week's (or more) worth of development behind - the fry was tiny with a huge attached egg sac. Needless to say - I let her grab that fry back up and will let her hold it another week. I haven't stripped her completely - there is probably a few more fry in her mouth but I'll wait to get them for now.
Any possibe explanations for this? Could she have spawned again about a week later, and had another fry or two?