Well, depending on the state, most have to give money back for an animal that has medical problems or dies shortly after purchase. It depends on the state so i could be wrong. Telling you of the issue could be because they don't want you to realize the problem within that certain time frame for return.
But, if the place has a good reputation than i would not worry as much. If it was a petsmart or petco i'd worry alot but if you trust them then by all means.
Personally, i have not had regurgitation issues except for sickness and once with heat issues. It's uncommon for a healthy snake to regurgitate anything appropriately sized, but not unheard of. The hair should not cause a problem for the snake because their 'mucussy' erm... snotty stuff and stomach acid USUALLY, but not always, would make their fur lay flat and smooth, not like an alfalpha do which would irritate.
Seeing as though i do not have first hand experience with an issue like unusual regurgitation, i'm not possitive. It seems to me like there would be an underlying issue that would cause regurgitation, but i'm no expert just a hobbyist
Feeding every other day seems very excessive for a long term thing.