Hi there - I am no "pig expert" but have kept weaners for the house for over 20 years now. Not every year mind, just when I have eaten my way through the last lot.
Although I now specify whether I want males or females (normally males as I find they are a bit cheaper generally, and grow a bit quicker) when I started, and before the internet was there to give us so much information I generally bought what was advertised in the local paper, so they were often mixed sexes.
I must say I never had a problem with any of them, though they were mostly traditional breeds. And they just went off to slaughter when they looked like a nice leg of ham on the trotter

, or when I just couldn't stand the trouble of looking after them any longer (Six Iron Age pigs in a muddy pen fenced with electric wire as winter is setting in ......

)
I wouldn't worry too much, but if you are into that sort of thing you might be able to get a bit of a refund, or maybe something off the next ones if it was a genuine type of person you were buying from
Enjoy keeping them, and don't fall in love with them too much, I found it very hard when my first two were slaughtered.....
All the best
Sue