Probably some enemies not "very far". You can go see if they are directly hostiles there (Three guy with bikes and melee weapons near the main road). For me, it's generally them who "create" this bug around V's apartment (you can kill them to be "safe" for a while, but they "respawn", so the bug could appear again).
Anyway, all of this "random" red map bugs come from this bug of enemies who appeared in 1.3+