These are the rewards for picking up the "level up" posts from your neighbors' walls:
Level 1 -10 - 5 xp
Level 11-20 -10xp
Level 21-30 -15xp
Level 31-40 - 5 xp
Levels 31+ just show their associated titles instead of a star with the levels on them.
Here are those titles:
Level 31 - Impressive Guardian
Level 32 - Superlative Guardian
Level 33 - Accomplished Guardian
Level 34 - Consummate Guardian
Level 35 - Peerless Guardian
Level 36 - World-Class Guardian
Level 37 - Unparalleled Guardian
Level 38 - Excellent Guardian
Level 39 - Oustanding Guardian
Level 40 - Matchless Guardian
* Don't forget you can also pick up 5 xp from your neighbor's reputation level up wall posts
(The icon look like a heart)
