Is EXP for retainers working as intended?

I'm really confused with how retainers gain EXP

Have included a screenshot, but basically what has happened is

2 of my Retainers are the same level

Both went on "Quick Exploration"

ironically both came back with the same item, one was HQ and one was NQ, but NQ gave me more exp than the HQ one @.@ but the same happened yesterday when one came back with a lvl11-15 gathering item and the other came back with a lvl40 green tank gear, the gathering item gave me more exp than then gear?

so really confused on how the quick exploration exp is gained, so is it a pontential bug or is it working as intended?

[IMG]http://i1021.photobucket.com/albums/...015_100157.png[/IMG]

Quick exploration exp has a widely variable range
I level up mine with regular ventures