If a bowler can "feel" 1/32 of a difference in the span, then they probably have the wrong pitches/span combo. Especially if they use inserts, seeing as though an insert can wear down at such a dramatic rate, depending on the bowler, the span could shorten by 1/32 within 20-30 games.
Also, just a slight bit difference in bevel at the top of the hole can make an accurate hit of the span "feel" like it's short or long.