Did you check where the cable runs under the bar tape, pressure as you grip the top bar over time can squish the cable housing a little and that causes it to be "sticky". Long shot I know.
Apart from that maybe bent it slightly by catching the deraileur arm while chaining up or resting the bike against stuff. Wheel and cassette aligned but derailuer is just slightly out.
Did you check where the cable runs under the bar tape, pressure as you grip the top bar over time can squish the cable housing a little and that causes it to be "sticky". Long shot I know.
Apart from that maybe bent it slightly by catching the deraileur arm while chaining up or resting the bike against stuff. Wheel and cassette aligned but derailuer is just slightly out.