Not an expert, but have a think about these points, only you'll know whether or not they're relevant.....
1) You mentioned using 40 flap. What was the power setting during the last part of your approach? If you were at or near to idle i.e. a glide approach, with 40 flap then the pitch change to flare would be large and difficult to judge accurately.
2) Regarding the stick force to flare, were you accurately trimmed for the recommended approach speed with Flap 40? I've found similar problems when flaring a PA-28 with full flap (and being out of practice) - I thought I was accurately trimmed but wasn't and only really found out when the control input to flare was much higher than expected.
3) How long was your final approach? I'm not suggesting a 'cross-country' final approach, but did you give yourself enough time to get comfortably aligned and trimmed? Or, was it a rushed, tight circuit?
4) Finally, after 1 hour you must have been pretty fed up. I guess that wouldn't help at all. If you were tense because it wasn't going well, then it would be even more difficult to get a good landing in the bag. Don't press-on with more circuits if it's not your day. Better to make it a shortened trip and try again tomorrow. Just accept that we all make bad landings from time to time and don't let it dent your confidence. Of course, a quick check-ride with an instructor might be all you need.
Hope that helps
WUT