I have taken the Gungywamp hike twice with tour guides. One was with a member of the Gungywamp Society. Neither tour guide mentioned the heart or showed it to us. You could do an internet search on Gungywamp Society and find their Facebook page. You could also try contacting the Denison Pequotsepos Nature Center in Mystic Connecticut as they now arrange the tours.
I am not sure in what context you saw the heart. Is it possible it was not discussed as it is new vandalism rather than part of the original site. It is on private land, but there are people who sneak in there unescorted.