before you took the lid off there was more pressure in the open space from the initial vigorous start of the ferment so your airlock was perculating. No that youre a few weeks in and probably near the end of primary there is much less gas released, probably just barely enough to keep your melomel blanketed but not enough to up the internl pressure enough to cause airlock bubbles. Doesnt mean ferment is done, also doesn't mean that it isn't.
Since you're going on a month I wouldn't go in there stirring it up really but give the bucket a gentle swirl with the top on to see if it wants to work a little more, then take a few hydrometer readings, about 3 days apart. if they are all the same, rack into secondary (good time to add some cherries if you have them to enhance the flavor) and go on from there, it doesn't sound like anything is wrong.
Watch and Listen to your Mead....It will tell you when the next step is.