surfers hiding behind the peak

out a couple of days ago in crowded but perfect strandhill. good bit overhead and howling off-shore. being the below average surfer that i am on those kind of days I was waiting ages to catch a wave that wasn't a drop in. pulling off of loads of potential waves because hoots coming at me from guys closer to the peak.
finally a wave came... i paddled hard to get deep on it, thought to myself "surely no one can be deeper and make it"
took a quick glance over my shoulder just before standing up and couldn't see anyone (although would have been hard considering the face full of spray anyway). got on to the face and feelin great, right before feeling a hand on my arse of someone who had taken off deeper trying to stop a collision.
luckily i knew the guy and instead of getting angry he just had a good grope and laughed it off.
anyone know if there was anything i could have done to prevent this? there was quite a bit of speed involved here and could have been pretty serious. knew there was other people paddling for it but was positive noone could have made the section, and am pretty good at making sure to always take a quick glance before taking off. very rarely drop in.
finally a wave came... i paddled hard to get deep on it, thought to myself "surely no one can be deeper and make it"
took a quick glance over my shoulder just before standing up and couldn't see anyone (although would have been hard considering the face full of spray anyway). got on to the face and feelin great, right before feeling a hand on my arse of someone who had taken off deeper trying to stop a collision.
luckily i knew the guy and instead of getting angry he just had a good grope and laughed it off.
anyone know if there was anything i could have done to prevent this? there was quite a bit of speed involved here and could have been pretty serious. knew there was other people paddling for it but was positive noone could have made the section, and am pretty good at making sure to always take a quick glance before taking off. very rarely drop in.