Roof weight limit?

Had to climb on roof the other day to install hard start capacitor in AC for generator. I didn't really think too much about how much weight the roof could handle, after all, there will be maintenance to do up there on a regular basis. I didn't stand, but mostly crawled and scooted around to get AC cover off and had to kneel in order to put capacitor in place. At one point, moving back I placed my hand down to shift position. I heard a mild snapping noise from under my hand. Could I have cracked something or could this have just been normal giving noises from roof? I'm about 205 but don't think much weight was no my hand at the time. After that I was careful and simply scooted around while sitting.
I could not find in my documentation anything about the roof, weather it's walkable or weight limit. If it's not designed to support a person, how is someone supposed to re-caulk or do maintenance if the roof is not supposed to support any weight?