Track numbers out of order ?

[ShiroiNeko]

Is there a problem with the track numbers?
Over the last week or so, starting at 594, the track numbers are rather strange, jumping numbers and duplicating ..

Recent track numbers, in order of use

593 Japanese Culture Class 50
594 Newbie 45
595 Not used so far .....
609 Beginner 2 45
596 Audio Blog 57
597 Lower Int 45
593 Used again for Lesson Int 72
598 Not used so far .....
600 Beginner 2 46
600 Used again for Audio blog 58

Don't know if this is a numbering issue, or a bug with my podcast feeder ( Juice )
Its not a big problem, but I do use these numbers to keep track of my downloads.