Not stretching before an impromptu 5-minute dance session: good to go.
Not stretching before a long but light dance sesh: probably not a good idea, probably still be fine.
Not stretching before a long, intense dance sesh: very bad idea.
I think I pulled something. ..
I think need start stretching everyday at the start because I can never seem to predict when the dance mood will hit me. Better to be prepared for it anytime.