Got some clear PLA a little while back. Spooled it in my usual way around a spool from Makerbot. Turns out the spool I used was too tight, or maybe I spooled it too tight, and it resulted in the spool cracking into smaller and smaller segments near the end. Lots of air prints resulting from this.
In the future I'm either going to use a wider spool or print spool holder that is bigger.