The light blue tokens are time based.
This means that they can be found for 2 hours a day, and the hour depends on their number. (Think AM and PM hours)
For instance if token 17 is a time based one, you could have a chance to collect it on 17th or 5th of each game month.
This means you could find it on December 22, but not on December 23.

Other examples:

Token 3: December 3rd and December 15
Token 9: January 9 and January 21

For tokens with a number higher than 24, you have to apply some simple math.
Think that the number represents the hours, and subtract the full days from it.
So 38 = 24 + 14, therefore token 38 behaves like token 14.

Token 24: January 12 and January 24
Token 26: January 14 and February 2
Token 47: January 11 and January 23

PS: To sum it up, if you have a lightblue token, it is quite rare and you should ask for a higher price than for the others.