Aborted Takeoff!

Today I was flying an Cessna 172 that I had never flown before. One of the other schools perfectly good airplanes, just not one I had flown before. The weather was not very cooperative and the Eastern Shore was socked in with fog and low viz. Going West appeared to be okay and my plan was to take a passenger up toward Gaithersburg and back to Tipton. Once I preflighted and completed the runup, it was time to depart. I lined up on Runway 10 and throttled up. There was another Cessna 172 on Downwind who had just announced he was making a simulated engine out approach. As I accelerated down the runway I could see that the airspeed was building up normally. At 55 knots I pulled back to rotate. The stick force seemed a little rough and in the moment I had to think about it, the stall horn sounded. I could tell that the airplane was "mushing" and not ready to fly. As I continued down the runway I was in ground effect just a few feet off of the deck. I wasn't going to get up anytime soon and realized I had to abort. I pulled the power off and pitched up a little to get into a flare. I was able to float the airplane down and land with room to spare. I rolled out to the end of the runway and turned off, wondering what just happened but very excited that I did the right thing and had a successful aborted takeoff.
Later on I contacted my former instructor and had a long conversation where I detailed what had happened and the possible problems that I had. We agreed that the combination of heavy weight & balance, air temperature, and premature rotation on my part allowed the airplane to fly into ground effect and that was it. Judging by the lack of lightness in the nose and the heavier than normal stick force I felt, both of those on the takeoff run, this seems to be the most likely explanation. While I welcomed the experience of the abort, I would have liked to have managed the takeoff phase a little to better to have avoided it altogether.