Occasionally it happens, and they have to manuver their jaw to get around it. It shouldn't be a huge concern, but just watch to make sure they get it down. Usually this happens with "breech feeding" or swallowing from the bottom up. When a snake swallows, they usually swallow from the head down and as they swallow the lags just are forced against the prey items body, because that's a natural position. When they breech feed, they swallow backwards and sometimes the arms or legs are not forced into a natural position and it makes it awkward for them to swallow.
Hope this helps!