Mischievous YWG or is something wrong?

[tlhood]

I have had a yellow watchman goby for almost a month now and I've noticed some behavior that I am unsure about. During the day he is still pretty shy and doesn't venture far out of his and his girlfriends cave (firefish). He has burrowed a couple holes, but I noticed he filled one up today and has resumed bunking with the firefish. He eats every day, I generally feed him twice a day, alternating between flakes, mysis, and brine.

The behavior that worries me is that when the lights go off for the night (the tank is in my room so the moon lights go off too) I can hear him jumping. I have found him in my overflow box several times. I have remove it for the past two nights because I worry he might get hurt pressed up against the grate. My tank is an rsm 130 so it has a full lid, however there is a one inch gap between the lid and the rear filtration compartment. It worries me that he will jump into the back. He also seems to like to rest up against the grill? Of the overflow. He also seems to swim around the top of the tank at night, tends to rest on my return pumps, and swims around my clowns when they go to their corner for the night (also at the top of the tank). There is plenty of live rock with hiding holes and open sand. I don't see him sifting that often.

All my corals look healthy, my firefish and clowns look and behave normal. Ammonia nitrate nitrite all 0, phosphates are a bit high as I feed them a lot, around 0.2. Temp is 78 and salinity is 1.024.

Is my goby just a bit of a brat, or is this totally abnormal behavior?(the swimming at the top at night and resting against the overflow).