Opiates and benzos are indeed a dangerous combination. At the doses you took I wouldn't imagine a serious risk, however the real danger often occurs due to the fact that your memory and judgement are impaired when you take benzos, so while you may intent to take 3mg of clonazepam and 30mg oxy, in your drugged state you might decide to pop another few clonazepam or more oxy and die in the process.