Changing the coolant breather valve

[shlim8]

I've been losing coolant... by not much, but still at a consistent rate....

After further investigation, I discovered that the rear boot lid above the coolant cap, is wet from condensation. After taking off the flat plastic piece, I noticed that the 3 of the 8 bolts that lock down the breather valve seem to have whiteish sediments and looked like it might be leaking from there. The is almost no sediment from the top of the valve.

When I used a hex bolt to check the bolts, they were only hand tight.....

As the bolts are probably screwed into plastic, I refrain from tightening them...

QUestion is, how tight should those bolts be ?? Any reason there should be some leakage from the bolts ? Or is it a sign that the 2 O-rings are deteriorating ??