Blast from the past: Unit 2 was reported as potentially re-heating in February 2012 (link is active but content of article is no longer up):
Fukushima's No. 2 reactor may be reheating. Japan today. Feb. 13, 2012 - 09:15AM JST http://www.japantoday.com/category/national/view/fukushimas-no-2-reactor-may-be-reheatingI have been assuming that the spiking readings from unit 2 reported recently were simply a function of TEPCO finally achieving access to high-radiation areas in unit 2.
[excerpted] "Temperature readings at one of the crippled Fukushima nuclear reactors have risen above Japan’s stringent new safety standard but there was no immediate danger, its operator said Sunday."
But perhaps some of the missing fuel from unit 2 is in water and is still fissioning?
I must say though that unit 2 never produces as much visible steam on the webcams as unit 1 and 3.