i'm new to homebrewing and so far i just use a plastic bottling bucket with the airlock lid to ferment my beer, instead of the glass carboy. usually when i brew it, the airlock bubbles some and a bit of foam gets up in there.
the other night i was brewing up a scottish ale and after i put it in the fermenter with the yeast and put the lid on, the brew was fermenting so aggressively that it was causing the lid to pop up in one spot. i tried to correct it as often as i saw it happen, but it still did a few times.
was this normal? was this caused by a sanitation problem? and finally, is my beer still safe to bottle up and drink or is it ruined now?