We've been there. We say she can go to the loo on her own if she needs to go but we don't go to her. Essentially she's using it as a stalling tactic (next is they need water, they need their covers on, they need their favouritest-ever book from the depths of downstairs etc etc).
DD2 is now starting with all of these too (not yet 3). We're wise to her and put up with no nonsense (poor wee thing!)