I was talking to a friend who does psychadelics all the time and he told me its possible to get HPPD from marijuana as well, not just heavy psychadelics... This is due to the fact that Marijuana is considered a psychadelic.

When searching the term psychadelic drug in wikipedia they say:

"Cannabinoids (CB-1 cannabinoid receptor agonists)

The cannabinoids are Tetrahydrocannabinol (THC) and related compounds, which are capable of activating the body's endogenous cannabanoid system. Some effects may include: general change in consciousness, mild euphoria, feelings of general well-being, relaxation or stress reduction, increased appreciation of humor, music and other art, joviality, metacognition and introspection, enhanced recollection of episodic memory, increased sensuality, loss of inhibition, increased awareness of sensation, creative or philosophical thinking, disruption of linear memory, paranoia, agitation, and anxiety, potentiation of other psychedelics, increased awareness of patterns and color."