I have been using heat wrap for years and it doesn't really produce much smoke, as much as it smells when new. My guess is that since the DP was off the car, that something else might have got on it (like oil, PB blaster etc. ) Drive it, monitor it and it will probably pass. If you are really skeered about it, unwrap it.
BTW, there's nothing under the hood of a WRX that can't get wet. You just don't want to hit the cast turbo housing or exhaust manifolds with cold water when they're hot, as there's a risk of cracking them.