Rusties DOA?? Mysterious death? Or murder?

Hey. I bought 3 small Rusties today from a fairly reputable LFS that I'd never been to. Excellent aquatic section, wonderful filtration, very healthy looking fish, so I picked up 3 Rusties to start my 55 back up. Went back to work, got home @ 3 hours later, checked them out, and the two smaller ones were almost dead, upside down. The third is larger--a good 3"; the other two are not quite 2", with juvenile bodies. My thinking is, the bigger one just bludgeoned the others to death before I could get them home???? (Shoulda coulda woulda---separated into 2 bags at the LFS). I'm sure I can get a refund, but do you think this is the possible death scenario?? The big one is fine, acclimating. 3 hours is, I think, the longest I've taken to get fish home, but they were in a double-bagged opaque plastic shopping bag, carried them quietly into work, then home. ?????? The mystery continues . . . . Thanks!!!

Thanks, stingray, you never steer me wrong ( )-- you and LoveMyKribs!! Such bad luck with everything, lately. Determined to do this mbuna right!! Continued research--I am very drawn to the rusties!! (as i recall, they were one of your original recommendations!)
After looking over them veeery carefully, I agree with you--there is no exterior sign of aggression on either one. I think the small size/youth of them combined with the extra hour or so (oh, why did I go back to school just to pick up some papers I didn't even need?)--so tomorrow, well, today, I'll take them back (those little half sized zip tops are great) and get some more when they come in. The guy in the fish section (who is extremely knowlegeable, as is owner--I love this place!!) recommended having around 6 or 7 along with the Yellow Labs they'll be getting in--@6 or 7 of them, too (end up with odd amount). I know these are relatively small fishes, but do you think that would be too many? I did ask if I could return males if there were too many--YES.
The large rusty is doing great so far, I acclimated him and got him in a quarentine tank (even tho the 55 is still empty) as I'm finishing up the seeded/Bio Spira cycle. I don't care what anything says, wanna make sure parameters are spot on.
thanks again!! saw another shot you posted of your tank--ummm, sand shots post--it just looks so good. Can't wait to see how the plants flourish--I'll add on later ($!!) later tater. . . .~rosita