Either might report but if you were in Class G, ATC would really not be interested in "dobbing you in". A lone complainant on the ground would have to have been A) incensed enough to even care B) Have read your registration and some way of verifying your height to have enough credibility for the CAA to begin looking into it.
As you didn't blatantly bust the 1,000 foot rule by much, I would open another beer and stop worrying. Learn your lesson and accept that you have made an honest mistake.
And fronted up to it on this website, which is of course likely to result in you being put into the PPRuNe village stocks and pelted with rotten fruit and ribald insults, any minute now.