@Don that happened at the end of last month but doc said I can't ride a bike for at least 2 more months.
@Daniel, the rear tire is 2 years old (purchased from treatland) the front one is original (about 6 years old). But it was stupid idea riding while road was still wet.
The thing about brake drum is - after it rains the brake is kind of rough when it grabs, sometimes even makes squeaking noise, going slowly and applying brake to scrape it off solves it, this isn't the first time rust on brake drum caused a fall, back when I had Tomos A35, similar thing happened only that time when I applied rear brake, it grabbed so much that it actually tore off metal clamp from the brake drum and tangled the brake cable wire around causing bike to fall, only that time there were no injuries.
Thanks guys. (edited)