Probably a culmination of different things but be careful of attempting wrist curls with your
max load if you've not gradually built up wrist and tendon strength already.
I personally would only attempt a personal best every 2 weeks, you'd be amazed at
how much power is lost after your first attempt (about 20%).
Also make sure when attempting P.B. wrist curls that you are doing so from fresh following
a very light warm up.
All activities and training affects forearm strength (training, arm wrestling, driving,writing e.t.c.)
therefore it is not uncommon for your forearms to have different levels of power from week to week.
From your own case m8 it sounds like your arms are still tired from the N.Y.C., i would have given my wrists
at least 2 weeks before going all out on them again.