Better to get them sorted soon rather than later. Best case scenario is a lack of oil in the lowers, the stanchion relies on a layer of oil between it and the lower. If you have low oil levels this gap will not be filled, and you’ll get a knock.
Best way to check… Turn the bike upside down for 20 minutes or so, then try rocking the fork again. If its gone, chances are you just need to top up the oil.
If not… Bushings are likely worn, and likely your stanchions are too.
Easy to top up the oil yourself if you look about, or just drop them to Loco, he knows his stuff and they’ll feel better than when they were new.