no we didn't.
to be honest, we were really close to absolutely sure there was nobody underneath us. the person would have had to have skied (grammar?) a completely illogical line in a very brief instant and hid behind that rollover that we could just not overlook from the very point where we were when we set off the slide.
the other group that we asked on the contrary had a very good view on not only the very slope behind the rollover but the whole path. so we were absolutely positive we there was nobody caught as soon as we spoke to them.
i think if we weren't the party that had triggered the slide but just bystanders we wouldn't have worried. but if there is just the slightest chance somebody got caught you just have to make absolutely sure it is not the case. at least i had to for a very egoistic reason: to be able to keep on living with a clear conscience like i had lived before.
edit: oh and after we made sure nobody was caught I was actually worried somebody who had seen the incident from the cabin would call in for mountain rescue. and what would it help to report to the patrol. they wouldn't know more than we did. on whose knowledge would they decide to take actions or not if not on ours. so to us it did not make a whole lot of sense. furthermore i think they must actually have taken notice of the slide since you have a pretty prominent view on the laub from some station. if not the decision would still have been up to ourselves anyways.