Originally Posted by xluben
These are good pictures and a very common problem. Even at stock boost this can occur, but any increase in boost makes it much more likely. A bit of oil in these components is normal. I wouldn't worry about it, but maybe check it once in a while because that does look like a somewhat decent amount.
EVERY 08+ WRX should remove those rubber end caps from BOTH ends of the throttle body hose. You should also add a zip to to the vacuum line that goes from the top of the BPV to the back of the intake manifold. The nipple on the intake manifold does not have a barb and can easily slide off.
I wonder when Subaru will finally make a production change to rectify this issue. It seems there are three common problems people have when increasing boost (they can even occur on stock cars as you noted)
1. Bypass Valve leaking
2. Plastic end tanks separating on the stock TMIC
3. This problem (throttle body/IC hose popping off)
Fortunately the TB/IC thing seems to be an easy fix. I will most likely follow your advice and remove those POS end caps. I will probably invest in some t-bolt clamps as well.