It seems that whenever I go to nurture my pets in the hatchery they always come up with 'this pet is weak' statement. It's happened for quite a while, I think it started just after the changes to nurturing but I'm not entirely sure... It doesn't seem to happen when I go nurture someone elses stables either. Am I just weirdly 'lucky' in this respect (or loosing my mind ^.^') or is there something else going on?

It all depends on what the pet's lowest stat is. If I recall correctly, "weak" means the lowest stat is strength so if you check out the pet's profile, I imagine that'll be the case.
Might be that you've been using a low strength male to breed with multiple females, the species has a slightly lower strength based stat (I have noticed that certain species lean more towards certain stats but it can be easily balanced out after a few generations) or the stat additions when the generations have hatched have leaned away from strength purely by chance.

Oh! Ok, thank you! I'm glad it was nothing serious. (Though maybe I ought to pay attention to these kinda things more... ^.^')

Oh! Is that what determines that? I never realized! I always thought it was random, thanks so much for sharing this! Goodness, I've been a member since two days after the site went live and there are STILL things I don't know!

You're welcome :)

I only found out recently myself (during the last festival) as you can increase a pet's statistics by nurturing it as a hatchling (I think its about 4 nurtures for one stat point increase)...

In the following scenario all the nurtures would focus on strength and working out with the pet until strength reached 22 and then the nurtures would be strength and dexterity nurtures:
Strength: 21 (21)
Intelligence: 24 (24)
Dexterity: 22 (22)
Agility: 24 (24)

Oh! Very interesting, I had no idea! I didn't pay that much attention when I had hatchlings to nurture [I need to get my space under control AGAIN]