Yellow Tang in trouble??

I am new to keeping marine fish. I have just finished cycling a 30 gallon tank with a very basic setup. I have a whisper power filter, Seaclone 100 protein skimmer, fluorescent lighting (changing that soon), and about 30 lbs of crushed coral and about 6 lbs of live rock. I put a yellow tang in about a week ago and he has been doing great, eating well and pretty active. Tonight I got home and he was shooting around the tank more than normal. I fed him and he ate a normal amount. Is it normal for these fish to dart around and stop suddenly and point their mouth up a little and stir the rocks up with their tail? I know this is a vague question but I am very new to the marine scene. Thanks for any help.

Rob

by the way, salinity is about 1.022, temp is about 77. I am going to get a full water test tomorrow.

I was thinking the same thing, I don't see any ich, breathing seems a little heavier than normal, but I have not really been looking close enough to figure out what is 'normal'. Thanks for the reply, I will ask my lfs tomorrow what he thinks.